Thoght I'd better let you know how the modified dist worked out. Warmed the motor up nice and pulled the existing dist out, gonna tear it down tomorrow to see if it was stock. Dropped in the modded unit, pointed the can in roughly the same position and fired it up. Idled really smooth, left the vac out as Daves instruction, and pointed my SnapOn gun at the damper and this is what I found; at 2600rpm I got 32deg of timing, at 3000rpm I got 35/36deg, after that, say 3250rpm, I did'nt have any more.
Let the motor idle at 850/900rpm and checked initial, it was dead on 20deg, which means that F.B.O plate gave exactly what it promised, holy shit
Time then for a drive ............
Out in the 30mph limits it ran very well, smooth off idle, hardly any lurching in too high a gear, chirped or span the tyres a lot tho', pushing the pedal down just a bit too eager in 2nd or 3rd just shreds rubber, althogh the diff does'nt seem too good at keeping both tyres hooked up.
Out off the limits it seemed sort of urgent on the throttle from low revs in a way, like it would gain speed say into moving traffic very easily, just short shift it and in no time at all its trundling along at 60/70mph.
I did floor it in 3rd to see what it felt like, it pulled very well, still have a slight hesitation going to full throttle, nothing to do with the dist I'm certain, abd when it did start to rev out, say 4500rpm it was charging fairly hard. Bloody speedo cable broke but I guess around 80/85mph, whatever it all seemed vey easy.
Fabien is right about the feeling behind the wheel being a little underwhelming, the enhanced lower end response and power makes the upper rev range feel less extreme somehow.
Anyway I say I have made a good improvement, the lack of vac makes no difference to drivability as far as I can tell, started from hot ok, so I'll stick with it