Three Five Hundred 1971 Lovely Brown Beastie

Just think how sweet it will be once you are motoring safely down the road. The brakes should still be OK since your previous work on them, once you check the quality of the fluid and if they need bleeding. You seemed very close before to getting on the road, so press on. Looking forward to more updates.
There was a bit more progress as I managed to get a 4.0 from a disco. Not sure whether to just use just heads or rebuild the entire engine to make a street sleeper. I need a to run confidently on unleaded.

I did get it running but it kept blowing water out. Discovered all the water jackets are clogged with wrotten anti freeze. Need to start cleaning everything. Gearbox probably needs to be fettled with too.

Brakes I'm fairly confident with so as you say should just need bleeding through again.