currently i have a 350 block bored .40 over and barely broken in. i added a set of 462 heads with the small valves off a 66 vette. they were rebuilt with stock replacement parts other than a set of crane aluminum 1.5 roller rockers. Also i have a edelbrock intake with a notch in the plenum divider for better fuel distribution a speed shop did years ago. on top of that is a vacuum secondary edelbrock 750. The cam was custom ground with .480 lift on intake and exhaust, but cant remember any other specs on it. Finishing off is a mallory mag pickup distributor with HO eletronic coil and multispark cdi box. My question is with that setup what would i need to replace to achieve 400 hp?

 

You don't know the cam specs, and probably not what type of pistons you have, or your compression ratio either? That makes it a little hard to know what you're starting with.
Get your c.r. in the 10:1 neighborhood, sell those small runner 327 heads, and get a good set of aftermarket aluminum heads. I've done h.p. comparisons on Desktop Dyno (I know, not bible, but good for a head-to-head comparison), and AFR heads came out on top.
That should get you in the 400 ballpark.

 

oh sry forgot to mention alll that. I have hypereutectic pistons w moly rings. Compression ratio is 10:1. I am also looking to make this power below 6000 since its a street motor. AFR 195 were the heads i was actually looking at. Would that be a good choice or 180? id like to maybe build onto this setup so i want some heads that still have flow left in them if i decide to step things up more. also i have hooker 1 5/8 headers going into a true dual 2 1/2 exhaust with turbo mufflers. 4speed muncie as well with posi 12bolt rear.