first thing i would do if i planned on swapping necks is get the new neck and fit it. Set the guitar up and make it playable.
As far finishing, i would put some laquer thinner on it just to test and make sure its not nitro (most likely it isnt) if it is you need to strip it. If not start by filling and repairing nicks scratches and dings and what ever else. Then scuff with 600grit then start spraying.
The heat gun blow torch method is a messing hard and unnecessary job.