Forced Induction - Supercharger advice needed

With everyones expertise I was hoping to make the rite choices in my Supercharger setup for my 550Rwhp / 500Rwtq 1968 Firebird. My decisions are as follows; Do i get a TH350 or TH400? I currently have a th350 which needs rebuilding, can it be built to withstand power ranging up to 660Rwhp? A stall converter is in question as well.. The current one i have is a custom 9 inch 4500 stall which is too radical for me.. Hoping to just get it cut open and tightend to around 3000 stall.. My cam is not as blower friendly as i would like either its a solid roller 240-250 duration 580-600 lift 112lsa. Can i get some opinions on a good grind cam for my appication?
Thanks -John

Turbo 400
I would go with around a 3500 stall, the cam seems a bit extreme. most cam grinds are 224/230 .581 lift/,589 lift on 114 or 115.

depends what you want to do with the car, daily drive, drag race, etc.