Best way to clean up the frame...........

Opinions please.....
I started to clean up my rusty old frame on my S3 Li150 yesterday with an angle grinder and wire brush but as I was doing it realized I'm just never going to be able to get in all the little nooks and cranny's there are and don't want to be leaving any rust to fester and re-grow, so if I can find someone local to me to do it I will, but whats the best way for paint/rust removal without wrecking it?? It also has some quite deep pit holes from rust, what could I do with those? (fill with weld?)
Shot blast? Sand blast? shot peened? Acid dipped? Vapour blast? Or some other way to avoid damaging the body panel.
And would you have it powder coated or primed/painted?
Thanks
I started to clean up my rusty old frame on my S3 Li150 yesterday with an angle grinder and wire brush but as I was doing it realized I'm just never going to be able to get in all the little nooks and cranny's there are and don't want to be leaving any rust to fester and re-grow, so if I can find someone local to me to do it I will, but whats the best way for paint/rust removal without wrecking it?? It also has some quite deep pit holes from rust, what could I do with those? (fill with weld?)
Shot blast? Sand blast? shot peened? Acid dipped? Vapour blast? Or some other way to avoid damaging the body panel.
And would you have it powder coated or primed/painted?
Thanks
