Ed, you are correct, the Spyders had the distributors on the opposite ends, 'cause mid-engine. But both the early Speedsters and Spyders had them on the camshaft.
The factory did indeed move distributors to the crankshaft with an auxiliary housing on later engines due to spark scatter AND vibration problems. I have some books to look it up if anybody cares for references. It wasn't a plain bearing only thing either.