I'm doing the body work on my son's 66 one piece at a time so had the same concerns. Regular primer will soak up moisture so is no good for anything that might sit outside. I went with epoxy primer (PPG Omni) and my supplier tells me it also seals.

The only concern would be that you will have to reprime before painting. The product sheet says "MP170 MUST be scuffed and reapplied if allowed to sit more than 3 days".

Talk to your paint supplier and tell them what you are doing and they should be able to suggest a primer that will work for you.


Dave
66 GMC- father /son project with the "GMC KID"
36 Chevy PU- 4x4 lifetime project
64 Skylark- wife says its hers