If you're looking for a DOHC head design, you might take a look at an old 3.8 Jaguar head, if you can find one. It's even the same displacement as your Chevy. Sounds like a very interesting project you have going.
I looked at that jag head, but the cylinder bores are way to off, thanks for the suggestion though.
Here are a few pictures of the 4AGE cylinder head I will be basing my designs on.
