dmw56
Busted and Rusted on Route 66
the 290, 343, and early 390 had one deck height and smaller head bolts, the 304, 360, late 390, and 401 had a taller deck height and bigger head bolts. check your intake to make sure that it will fit, if it is the 290 -390 the middle intake bolts will not fit to the newer heads and the ports don't quite match and vice versa. i know they look the same but there not.
odie
Yes, forgot to mention that. It's also very easy to tell which size engine you have the cubic inch is cast in the side of the block. I won't go into differences of the crank flange because that is way too confusing!!