got a few hours on the twin over the weekend. its slowly coming together. drive pulleys are half machined. i hacked up a rotted out old kawasaki set of pipes to give me some bends to play with for free and the simple exhaust solution looks like it will work nicely - 2 into 1 running below timing covers, front pipe extended over blower.
also got sorted in my head the routing for the blower. SU mounted on pressure side [rough mounted in pic] then long plenum cylinder running on right side of engines, spurring off to 2 cylinders. sounds simple eh... i bet it isnt to make work