if you're going for originality... the 235 is better.
the 230 is newer (not ALWAYS better), has 7 main bearing caps vs 4 main bearing caps... makes it a little more comfortable at sustained higher RPMS, the 230 has a bit more HP (I've seen it rated from 140-155), the 230 has an integrated full flow oil filter, versus a bypass filter, and I'm sure there are many more differences (but I'm no expert).
It all depends on what you want for that truck.
