Hi all, thanks to everyone for the suggestions and assistance. The Inter is finally back on the road after 5 months!
Unfortunately I exhausted everything I could think of, and even most forum member suggestions, so I was forced to admit defeat and take it to a professional. I ended up taking it to Craig at Dynalign in SA (He's a well known engine tuner in SA and his workshop is about 5-8 minutes from home.) After misfiring, backfiring, blowing loads of smoke and hobbling along I managed to get it to his workshop early one morning.
So what was it?
Nothing major and not just one thing, it was a jumbled collection of little errors, stemming mainly from the carby rebuild and electrical and very little to do with my head work.
Mixtures, timing, points, vacuum advance, coil, plugs. All things I'd played with individually and replaced here and there, but it needed a pro to realise replacing A might fix A, but now upsets B and so on. For example I fitted new points, plugs, set the static timing, and idle mixture, but it wouldn't run and the plugs kept fouling. Changed the coil with a GT40 (Don't do this ever - someone did mention that, I admit) which killed the points again.
So fixing this plus about 4 or 5 other incremental changes and we're running sweet! Only took him about 2-3 hours fidlling here, there, and everywhere.
I do need to readjust the valve gaps now as I had them stoo big to eliminate a head/lifter/pushrod issue that I thought may have arisen from the head rebuild.
Anyway, learnt a lot again, and realised however many years expereince I have playing around with old vehicles, sometimes you just have to accept your own limits and get a pro.
then ya forgot to click on insert.... good fixing by you... Sarge.