It is either a passenger car engine or a truck engine that has been retro-fitted with hydraulic lifters.

All 235 truck engines used solid/mechanical lifters.

Yes, any 18-bolt 235 head will work with your block. A 1956 and later head produces higher compression.

The oil-feed plumbing to the rocker arms changed over the years. Someone else will have to comment about what is needed for plumbing an earlier head to the later rocker arm assembly.