383 oh what to do
Most likely cost wise, staying with the 383 may be the best bet.
Having the Mains 'Align-Honed' is not too costly, and will ensure a 'square' base
for the internal reciprocating components.
Cam Bearings. Also no big cost.
Picking up a couple of Rods, again minimal cost.
I'm sure that you are planning on having the Internals 'Balanced' again.