Im embarking on a pretty rusty retro jap project shortly that comes with most of the repair pannels to get it solid.

Im planning on the car being a keeper and am happy plowing the hours into it but don't want to go to the effort of a bare shell rebuild and a lot of welding only to see rot return within 10 years. Ive got a good friend with blasting kit.

My thoughts are once media blasted whats best to treat it with prior to priming.

I have got a huge pile of PPC mags and im sure theres a rust treatment best of article in one of them, going to take some finding!

phosphate treatment if you are going back to bare shell from what I have read.

rust busters FE123

there was an article a while back in PPC or maybe Practical Calssics on a dip treatment. Basically a chemical clean to bare metal, then a dip primer. From memory it wasn't just a paint primer, more like an etch primer. Could be the phosphate one mentioned above. the results were very impressive. In part, the effectiveness must be due to total immersion ensuring everything is coated. It must also benefit from being done immediately it's been cleaned so no air time as bare metal.