Took the head off my 400 to the machine.shop for some work and they noticed a crack on it and said they could do what I brought it to them for but I might as well just get a new head. I was looking on Craigslist and there's a set of 915's for 600 (eek) and also a set or ported 906's for 350. I was doing some reading but figured I would put it out here to get options on what I should look for. I'm in no hurry so I can wait till something comes up that I want. Let me know your opinions.
The best flowing head is one from a Mid 70's 440. I think it's a 452, but DON'T quote me one the number. They already have hardened valve seats, and are the best flowing production head from Chrysler. They also are not too expensive usually.
The only thing is whether the combustion chamber is adequate for your desired compression ratio. You'll have to cc that to find out. I bet it's not too different than the 400 head.
The 452 casting is a 906 head with hardened seats. if your 400 had the original heads, that is what it came with.
Pretty easy to find, and like Rich said, are pretty affordable.
Ran across a set of 452's on Craigslist about an hour from my house... already been ported and ready to bolt on. He was asking 300 and I offered him 225 and he took it. Is there something I should look for when I go to check them out? Obviously check for cracks or anything like that but what should I be looking at to make sure they weren't ported like crap or anything. Any tips are welcome, thanks!
If they were ported by the owner then...hard to tell how they flow until you get it on your engine. If they were ported by a pro shop, they should have included a cfm flow chart of each port for the owner to have and pass on in the event he sold the heads. Thats' what my local shop does for its' customers. Port matching is so important and so is grinding down the valve stem boss inside the port. Not too much short-side radius shaping is needed for these heads to flow properly and too much grinding there will make the port flow like crap. Check the head to block surface with a good straight edge before bolting them on to see if there is any warpage there. If they have been planed already then an equal amount of material should be removed from the intake to head surface or else the geometry will be out of sync and further problems will arise.