Hi, you know a good motor to use if you are able to use a blower is a 366 tall deck bbc. The pistons are huge and can take alot of heat, and the smaller size is not as much of a factor with the blower. They can be had super cheap at the junkyard, and if you tear one up who cares, get another one. But they are indestructable!! I have always wanted to do this, they come in garbage trucks school busses kodiak top kicks and dump trucks.. They seem like they are meant for a blower, they already have the right compression ratio even... my .02