40', why would you want to hang egg beaters off the back of a 12,000lbs boat???
it could be done but i have no idea why you would want to do that. If you ran triple promax300 she might run 60. But you are talking like 60k worth of engines. You could buy a pair of hp500s with whipples and fresh bravos for that kind of money.
I know of one 38KV scarab available with 550hp big block. Late 80s nice shape not to pricey. I think there are a couple 38's in the classifieds too.