Sanding and painting. How did you do it?

[CarRamrod]

I've been on here for a while. I've been doing research to find the answers I need. I hate asking questions that have been asked a million times.

I'm starting to build my 240sx. I've torn it all the way down to the bare shell because some 16 year old drift wanna be decided to strip the car and do pretty much everything half assed. The engine bay is purple and hatch is a different color etc.

I was going to take the car and have the engine bay and underside sand blasted but I need some ideas to keep it from rusting while I put the cage in it, fix problems, install suspension etc. I just want to start with a clean slate.

How would you keep the bare metal from rusting without causing the paint shop too much grief? I was thinking about spray bombing it with primer but I know all that is gonna have to be sanded off which is more labor hours at the paint shop.

Any ideas? How did you do it?