318 Magnum
Is this a stock LA bottom end? Stock pistons and all that?
If so, I'd definitely recommend a thin head gasket to try and get the compression up. Mr Gasket makes one that has a compressed thickness of .28 (I don't know how well it seals). You might try having a small amount milled off the heads as well.
I'd also probably try the heads without porting to start with.
If you're not going to run headers or buy a big converter, this cam might be a better choice.
http://www.voodoocams.com/Product.aspx?id=1544&gid=287
You'd want to check to be sure the lift wouldnt cause problems with the Magnum heads though, as on the exhaust you'd be at .526 with a 1.6 rocker.
Steve