Right, cleaned everything I could, crank sensor (the one by the crank pulley ?), dizzy, rotor arm (both look as new), HT leads both ends, connections at the coil and the plug that goes into the dizzy (covered in oil).
The gap between the crank sensor and the pulley is .4mm, I think that's ok.

I reduced the gap on the spark plugs to .5mm, the car runs noticeably better, even boosts all the way, but still with a slight mis-fire and a few pops and farts !

I also noticed that plugs 1 and 4 were more sooty than 2 and 3, so swapped them round (1 and 2, 3 and 4). Just been out for a drive and 1 looks more sooty than 2 again.
Sounds like weak HT to the plugs to me, maybe I need new leads and a new coil ? Don't believe these have been replaced since I've had the car

I'll ask in the main forum if that sounds ok and how low you can gap plugs...