Went to the machine shop to pick up a set of rings for my flathead and the owner says he has a Hemi his son owns and wants to sell. Owner says he doesn't know if it's a 354 or a 392 but his son would know. The engine is complete and is not stuck, is there a appreciable difference in value between a 354 & a 392? I know nothing about a Hemi, can they be identified by external differences? What would be a fair price?