Thanks I’ve been shopping around this looks like a worthy option!!

This fuse box is a new product that uses newer style blade fuses. https://www.torquerestoparts.com/product-page/triumph

When you get a new fuse box, solder the layers together on the backside.

Good to know!

When you clean up the fuse box, before you clean all the contacts, remove it and inspect the back of it: the fuse holders are riveted to the wire terminals and they are usually corroded in behind. Not worth fixing - get a new fuse box!

Thanks Dan for your comments, Though I was sure that I had the items you suggested covered I confirmed, cleaned and tested each connection from the battery to the starter and ground, engine ground, fuse box, alternator the works. Not sure why or where but apparently I found the problem and the power is back, the engine starts and runs ok now. I’m working my way thru the fused accessories and cleaning up the connections at the fuse box. This has been a real head scratcher. Hoping for the best from here. Thanks!

I'd start by having the battery tested. They can read 12V with light ir no load but have a bad cell rendering them useless. 

Next, I'd recheck that new cable you put in, making sure it has no cuts for potential shorts, that the battery terminal is fresh, clean and tight and that it is connected to the correct solenoid terminal (silly things do happen). 

Next I'd check that the ground cable to the battery from the car body in the boot is fresh, clean and tight. Follow that up at the front end to make sure the ground from the engine to the body is also perfect in the same way. a failed or missing engine ground means that it finds its own ground through things like a choke cable, a speedo cable, a heater valve control cable or other path. 

After that I'd disconnect any power feed that isn't necessary for the engine to crank and for the ignition to function - no lights, no radio, no accessories. Then slowly reconnect until you hit a fail.

There's a remote chance something got mis-connected and fries something in the harness,

My bet is you forgot the engine ground after doing the clutch work.

 

Replaced the clutch flywheel and starter in my 76’ Mini 1000 Canadian thought all had gone well. Hit the starter and it turned over swell, put the plugs back in tried it again and a fuse blew and every thing went dark, everything. Replaced the fuse and nothing changed. Checking the odvious found I had 12+ volts at the battery less than 6V at the wing mounted solenoid. Found the cable from the battery had a spliced/repaired area where it ran along the front subframe to the solenoid so I took it out and replaced it with a brand new cable and started checking things as they occurred to me looking for the problem. Found that if I left the wires that run from the solenoid to the alternator the voltage disconnected the voltage at the solenoid battery terminal was batter voltage with no drop. Not sure what that tells me but does not sound good. Removed everything from the solenoid and the fuse box and started trying to isolate the problem. Haven’t found it yet and had to set it aside while I dealt with normal life things. Will be back in town next week and trying to come up with a plan the find the problem. !st I’m thinking of having the alternator and started tested and go from there. Would appreciate any suggestions. The very last thing I did was to connect the brown wire that runs from the solenoid to the lgnition switch and test for voltage there which at 1st was normal. Then connecting the white/red to the solenoid thought the starter would engage. 12v disappeared at the switch. Wiring harness was a mess when I bought this car and I replaced it 10 years ago has been working fine since.