Thanks for the LPG info. Did some more research and made a few calls today. Engine should be freshened anyway so I'm going to find out just how high I can safely go on CR with propane (LPG), then do up the heads with valves and seats rated for propane, then get Comp to do me up a roller cam for it! Talked with a tech at Comp this afternoon, should get a substantial increase in both torque and efficiency with the right head work and proper cam. Should work out quite well!
Did more work on the '57 body today, started putting the wheel wells in. I'll have plenty of room for 12" of tread width. Got to have the body and frame on their way to the sandblaster Monday or Tuesday next week, then back to customer work for awhile.....