Mini tub questions...

i got a 67 barracuda convertable & i'm going to tub it in aug. the gas tank depends on how big a tire u go with. i'm puttin on 29x 18 mickey thompsons & i'll have to run fuel cell. a good muffler shop will have no problems routin exhaust thru it. if u mini tub it & use a spring relocater kit u can keep your stock tank.