24's arent enough for a 400rwhp 347. 30's at least. You can make awesome power with a 347 and still be fine on the street everyday if done right.
Im planning a 10.7:1 347 in the near future. Ported TW heads, TFS R or victor 5.0 intake, jay allen custom grind cam, 1 3/4" longtubes, 75mm TB, 30's, 80mm pro m. Might get a fms rev extender and bump the limiter to 6500. Easy 120 traps and low 11's. Im doing it right, im not gonna put marginal 302 parts on a 347 and expect to be happy. I'll be using the CHP rotating assembly-cast crank, forged 5.315" rods and forged probe pistons. Goal is over 400rwhp. Still havent decided how radical I wanna go.