If you need something other than7.5" disks you are driving over your head

Buy new rotors. They're not that costly. and paint them before you put them on.  Let the new brake pads cut the paint off the rotor surface where it makes contact and the rest of the rotor won't rust.  BTW, old brake hoses collapse internally and trap the fluid at the wheel locking up the brakes or a wheel.   If you're going easy but want to blip it once in a while, get a servo/ brake booster and a kit roll of cunifer brake pipe and fittings. You'll need a bubble flare tool to make the ends. Don't forget to slip the fitting on the pipe before you flare it.  Save the old brake pipe in case you hate the booster or it fails and you want to remove it.

I"m not sure how the 7.5's will hold up with a honda lump but you'll find out.

I'm not sure what you guys are using in reference to brake fluids. I've been using DOT 5 Silicon Brake fluid for  4 decades now and have not experienced one problem. I use it in my mini's brake system as well in the clutch system. No problem, nothing.

As far as  2pot vs 4pot - The brake pad composition is a critical factor. That's the friction against the rotors. Also the composition- some tires are more slippery than others. The size of the tires specifically, the contact patch, the smaller the patch the less stopping. The mini has very limited choices in tires. Adding another 2 pots, (in reality 4 pots) is not going to make any difference if you are not going to address the issues with the pads and the size and composition of the tires. And we haven't discussed the operating temperatures...

While the 10 inch tires are the classic look and ride great, I feel they are squirrelly. They slip and slid. Going to 12s, you'll find that you'll get more grip. But you loose the ride and look.

Yeah - think silicone and type synthetic.. DOH !

 

The other one to avoid like the plague is mineral based, which is specifically warned against by AP Caparro et al.  I accidentally used some mineral-based racing brake fluid in Gertie as the label was unclear, and it destroyed the M/C, caliper, and wheel cylinder seals.  The system essentially emptied itself.

 

just to clarify - ALL brake fluid is synthetic. (it's polyethylene gylcol which is man made) but stay away from "silicon" fluids as they are typically not compatible with the seals and fluid you already have

Leaks and failed seals are usually down to the choice of brake fluid.  Some modern fluids are utterly incompatible.

Stick to Dot4 or 5.1, change it every 24 months, and steer well clear of synthetic and you'll be fine.

Markiss

Im just not quite sure how much benefit to expect from stock brakes to 4 pots. I feel like as said by Alex,it will be minimal if both brake systems are all new/proper.

Ive stopped the car with the 7.5s.They are gettinf iffy because i let the car sit too long. I always ran into brake issues though with leaks and air in the system. Wheel cylinders,hoses,etc bursting. Most is all replaced now.

The front rotors and pads arent that cheap,and if i dig in and end up in the rabbit hole,i dont want to regret not upgrading for a little more. Im just unsure how much it helps. I deffinately dont want custom wheels etc.

I was hunting down info on here and at the https://www.theminiforum.co.uk/forums/ as well, when I was thinking of either going with 10" or 12" wheels, and then which brakes to use. There's been people running more than 7.5" discs on 10" wheels. But be prepared to pay a mint for wheels to accommodate bigger brakes depending on how big you go..
But you could still go with 7.9's. You can go buck wild and go with MiniSport's R range brakes that are 8.15" with 10" wheels. Lighter brakes and will lighten your bank account quick too. 
Seen 10" Valtain wheels with 8.4" disc brakes. But good luck finding those wheels. But there are some custom wheels shops in the UK that make wheels that will accommodate larger brakes than 7.5",...if you're worried about stopping power.
I'm going with 7.9" MiniSport vented Aluminum callipers in front and MiniFin rear drums for my VTEC convert.
Depends how crazy you're going to drive the car and what kind of power you're aiming for (or have already). There's always going to be crazy times and temptations out there to get wild. I'd want 4 pot and maxed-out-diameter discs just to be safe. I wouldn't want to skimp on brakes, especially when tripling or quadrupling the stock power band. I was a little leery stepping down to 10" wheels due to having to step down from 8.4" brakes to smaller ones, when working towards making 170hp-ish. But I was assured that the 7.9's would be good. 
But to each their own.
Just my $0.02

there is a bunch of cool info here-
https://www.theminiforum.co.uk/forums/topic/70202-the-low-down-on-brakes/

Alex,thanks for your reply.What pads are you referring to? A specific brand?

In my head i was staring at how tiny the brakes were and really didn't think they could be that much better for normal driving or even some fast braking at higher speeds single time(not track type situations).I just cant see the lightweight/small tire width really needing much to stop it.Ive been chasing braking issues though for a while. Ive replaced all the lines,hoses,etc and finally bled it and had a nice solid pedal. 3 days later i come to the garage and there was a puddle under it ????

I've got 4-pots on a couple of mine, and std 2-pots on others.  not really much difference in the real world except for bragging rights.

Carbon metallic pads on the other hand...

I am running 10" wheels on my Vtec car with 7.5" discs currently. The rotors are a bit crusty and pads. Was thinking of trying to get them cut and put a set of pads on for now while i decide what i want to do.I just added a complete new rear drum assembly kit in the back all new so the back is done.

Im not sure if i should upgrade to the four pot aluminum calipers for the 7.5 assembly with vented disks? Does it make a drastic difference for basic street driving /quarter mile type passes where you aren't on the brakes repeatedly?