I would say a 255 in-tank pump should be plenty!! I wouldn't screw around putting in a inline pump, there very loud, and it aint worth it! lol
I got a friend with a 347, AFR 185's, 30LB injectors, and all the other bolt ons you can think of and a 100 shot of NOS!!! and hes running a 190Lph in-tank pump. And it runs great, and he had it dyno tuned.