For a nice street 347ci, 400RWHP is obtainable with out going crazy but it comes down to budget, drivabilty and usage... Then you can powder coat and add all the bling to make it a nice show piece.
Do you have any parts you want to re-use?
FWIW- I did a 10.7:1 comp, 333ci, stock AFR185, Stock un touched Cobra intake, RNH custom cam and on our stingy mustang dyno it made 383rwhp/404rwtq. The car is the perfect street car and the tq curve reminded me of a big inch windsor, it drives great, he pulls on his buddies 03 Cobra..lol Its also a monster at the shows, the engine is fully detailed and beautiful. Dont get to caught up in numbers, ....