The main concern is engine. The flywheel needs to be balanced, with the crank, and also dowelled, to stop it launching itself, through the engine!
All main engine parts, to be inspected, and sorted accordingly. Carbs will cost over £1000, to reburbish, alone.
Wiring loom needs making. I would make the loom more modern, for reliabillity.
How straight, is the altered chassis?
Its a lot to sort, but not as bad as some i have seen. The big inspection, will decide things, i am sure.
Andy.