double hump fuelies.
Could go a size down 307 onto 327 my pontiac has 327 heads on a 4bolt 350 ample grunt!

I would go some new, cast iron darts or alloys depending on your budget, towoomba foundry used to make some chev heads not sure if the still do them now, fullies are o.k but they are getting hard to get a good set now so demand good money so i would buy some cast iron darts excellent value for money, really for 400hp would not need porting, drop in some new valves,spring, retainers and locks and away you go.

hi monter. The Dart iron is good (as Byron said worth looking at) but there are heavy 52 lbs much more than a chev orginal type. They have got hardened seats,stainless valves and new springs ect (not 40 year old stuff) . If you went this way you'ld have to fit hardened pushrods as they run in a guideplate, not the cast iron of the head.A 64cc chamber and 180cc intake should ark it up. Unless its modifed more a bigger port might work. Also don't dismiss new bowtie's,very good with 184cc intake. Dave

I've never used the Dart heads, but those that have have told me they are good value for money and bang for buck. I think the original Darts were copies of the last of the factory Fuellies ie 291 slant plug heads.