Welcome back, Craig!

Pretty near everything except heads (some have used 305 heads on 350 - but need to check clearances first) and pistons will interchange. Manifolds, water pump cam shaft, timing set. Part number 3932442 is a common large journal (2.45/2.10) cast crank for the 305/350 with two 2 piece seals but remember cranks and rods need to be balanced as a set so don't randomly mix & match the rods.

All the bolt on, i.e., valve covers, alternator, fuel pump, etc.. interchange.

Have Fun,
Glenn