edelbrock heads on a 318

I'll play devil's advocate on this one...

Have you thought about the Edelbrock heads for Magnums? They have a 58cc chamber. That and a skinny head gasket would actually get you decent compression, even with the crappy stock pistons.

Its a more involved swap, because you'd have to buy AMC lifters, different pushrods and rocker arms in addition to the heads. Unless you paid Hughes or someone to drill the Maggie heads for your old intake, you'd have to buy a different one, but that Edelbrock Performer RPM Air gap is well, badass.

Keep in mind it takes 50 lbs off the front of the car, and you get a way better flowing head that would be worth something when you were done with it. Probably not a whole lot more expensive than having a ton of labor done to your stock junk anyways, especially after you buy valves and springs.

As far as the head being too big, they flow about what the TFS Twisted Wedge/AFR 185 head does on a small block Ford, and lots of guys make lots of power with those heads on a 302.

I've got a 318 in my Dart, and I've actually thought about putting off the 5.9 swap for a year and trying this same thing, just to see what it could do.