Well, spent today working on it since 8am, and finally sorted all it's issues out, it's now got much better brakes, better gearchange, all the suspension bushes have been stripped and regreased so they don't stick any more, the front suspension has been overhauled and softened slightly, and the back lifted up 1" so she now turns in properly, it's got a nice cold air intake, some scoops picking the airflow up off the doors to cool the ex. manifold on one side and the oil cooler on the other, and a new alternator as the old one wasn't charging any more. Sorted!
Spent 15 minutes on the test track quite happy with it at last, bar a tiny, tiny bit of clutch slip after a gearchange.
Fetched it back to the workshop, adjusted the clutch slightly, bingo, no more slip.
Back to the test track, give it some welly, change into 4th gear and 'BANG', snapped the input shaft clean off the gearbox.
Should have left the clutch slipping!