Sleeving 340 for a Stroker kit
I think the 409 is pretty cool. Weird, yes, but cool. For similar reasons I also like other engines of the era.
Ford FEs with the strange intake manifold that doubles as half of the valve cover gasket. Neato!
Any of the Cleveland 4v headed engines. Super cool.
Poly 318s are pretty cool too.
Max wedge high ports come to mind...