I have been in several later model motor home 440s and they all had pistons .080" or more down in the hole. In my opinion, not much is going to help that shy of new pistons. But, by keeping that in mind when choosing the rest of the combo, the low compression won't kill the power. Certainly not enough to go with the 383.

The biggest hurdle I have had with these engines, is trying to get a good timing curve in them without them pinging. They spark knock very easily. Must be because of a lack of squish.