Steve,
At least you are starting with a post 81. Being lighter and having 5 bhp on the pre 81's.
Mines 1979...doh! But it does have post 81 heads (more power!). Offset by a heavy bosch starter, a heavier flywheel, iron cylinders and a fat pilot! Oh, and those conical air filters do nothing for the top end....One day I will put my airbox back....
Good luck!