since you already brought the 72 home i'm assuming you're looking at the other blocks for parts?
on the up side, the 430 has the smaller combustion chamber ( higher native CR ) and hopefully has the 'big port' exhausts.
on the down side, the 430 oils the rockers by weeping through the shaft ( the 455's oil through the pushrods ), it uses a different size pushrod than the 455, smaller diameter head bolts and the 455 block may or may not be the 'double scallop' water passage arrangement.
IF the 455 is a 1970 it will have the same size combustion chamber as the 430 heads and you won't have any problems at the head/block/intake interfaces except for the possible double scallop issue. it might also have the larger stage valves but you won't be able to tell without pulling the head.
hire an engine man to do some basic porting and head work and the 1970 head will be better than the 430 whether or not the 430 has big ports.
now if that's a 71 engine it will have practically the same heads as the 72 and i'd probably try to deal with adapting the 430s.
of course the best option would be aluminum TA heads. those flow as good out of the box as a heavily massaged factory iron head and you're saving +75lbs. it also lightens your wallet at the same time so you don't have to walk funny.
The way to crush the bourgeoisie is to grind them between the millstones of taxation and inflation.
Vladimir Lenin
Government schooling is about "the perfect organization of the hive."
H.H. Goddard, Human Efficiency (1920)
Bookmarks