I got these from Moss Motors. They are actually stainless steel unlike others I have seen in the US which are chromed plastic? 

Now just need to find a used rearview mirror!

Or you could use riv nuts to hold them in place, just as with Doug's idea it makes it easy if you ever have to remove them as the riv nut is permanently in place.

Yes, make your selection and bolt them on. Two cautions. Some of the rectangular mirrors don't adjust enough to work mounted on the door. The PO of my car made that mistake. I don't know where he got them. I replaced them with bullet-style mirrors, from our host, which do adjust enough. The second caution is the length of the mounting screws and your roll-up windows. I lost some of the tinting on my driver's side window and had to go online to find shorter stainless steel screws to replace the ones which came with the mirrors.

Agreed.  With all the custom work already done on your Mini you should not feel tied to one style or another.  Select whatever you think will look best and bolt it on. 

For my car I made "nut bars" to go on the inside of the door skin.  The nut bars are epoxied in place and that gives me "permanent" threads to mount the mirror using machine screws instead of the sheet metal screws that come with some aftermarket mirrors.

Make sure you have a helper hold the mirror against the door while you sit in the driver's seat to determine if the mirror location works well enough.  (Measure twice, cut once) .

Hi Indifferent, it kinda works like this ... search I’net for mirror you like, buy mirror, bolt to car.....

I can see why you would be worried about originality  but cars like yours would not have had factory mirrors ...so you get to choose..

I’m much more interested in how the seat issue is playing out.....

Cheers, Ian

For reference, here is the pup: https://lh3.googleusercontent.com/-2nbRLVC6ggE/XfEseJPmknI/AAAAAAAABig/0_sbr6nR6jopQyFrEp_0M4CCe4oeaLDqQCK8BGAsYHg/s0/2019-12-11.jpg

Oh, and a SA mini pickup ... meaning no sliders, roll up windows instead!

Yeah, if I only had seams....mine are shaved

Carbon fiber?  On a Mk1?  To each his own.

Regardless, don't count on using the old holes.  Plan on making new holes for whatever mirror you choose and removing the door card to access the mirror's fasteners.

If you don't want to drill new holes, if you don't want to remove the door cards, and if you are willing to use something other than carbon fiber... consider the type of mirror shown in the links below.  The links are for mirrors that attach to the A-pillar seam covers.  To protect the paint you'll probably want to wrap some rubber, plastic, or leather over the seam cover before mounting the mirrors. 



Link to rectangular seam mirror.

Link to round seam mirror.

There is a vintage mirror type at attaches to the window slider latch bolt, no drilling holes required. Sold by mini spares, Mountney CDM5 Downton style mirrors.

Not sure...thinking maybe like attached or Magic Racing Mirrors (or like them, pricy) like I had on my lotus.... //www.gotuning.com/product_info.php?fPath=NSX_1&products_id=1665

All depends what type of mirror you're wanting to fit.
If Tex style ( not sure how they would work on a MkI ), you could always get MS to send you the measurments
//minispares.com/product/Classic/Body/Exterior_Trim/Mirrors/M99982.aspx?030501&ReturnUrl=/search/classic/mirror.aspx|Back%20to%20search

I'd have mirror/base in hand though before drilling any holes though.

The mini I have coming to me doesn't have mirrors, but I should probably install some. The holes were shaved so I won't know the spacing. So what I am looking for is general dimensions, e.g. the base that mounts to the door, distance between the bolts, distance from the body, etc. This is for a 1964. I am looking to put some CF mirrors on, but need these details first!

Any help would be appreciated!