roof rust questions

So heres the deal on my 72 dart. pulled the vinyl top and theres tons of rust with pin holes everywhere, the rest of the car is in great shape though. I'm trying to get this thing built on a super tight budget and want it to look decent, i've decided to put a new vinyl top on this thing but want to try and stop the rust from getting worse before i do this. im sure not being the right way to do it but after getting any loose rust off will using a rust encapsulator and then sealing it with rustoleum work for anything or do i need to go a different route. looking for good suggestions from you with experience.