I fully concur richsd, there are only a few engines that are acceptable for a GREAT replica, the original ones!
A few others are so 'over the top' you just gotta smile! A Hemi goes well in just about any application, for instance. A VW? Nah, I couldn't go that way!
I saw a Rat Rod the other day with a late 50's Olds engine. A breath of fresh air compared to the ever present GM small block.