Here's how I'd go about it.
Set yourself up with a little porting station. A dremel with a flexible wand and a handful of grinding cones works pretty well.
Then just spend some time smoothing the bowls out and getting a nice transition from the bowl to the valve seat. You can skinny the guide boss down a little, too. I'm guessing the exhaust ports are terrible like any other OEM casting so spend some time there as well. The dremel finish is fine but they don't make for pretty pictures. Hopefully your heads don't look as bad as these, lol. There should be an easy 30 hp just in minor porting work.
Then I'd have Comp grind a cam using lobes from their Xtreme Energy profiles.
Intake lobe #5442 Advertised duration 262. Duration at .050 is 218 with .493 valve lift.
Exhaust lobe #5232 Advertised duration 268. Duration at .050 is 218 with .456 valve lift.
Have them grind it on a 108 lobe separation angle with a 104 intake centerline. "108 +4"
I'd use a Performer RPM intake and 1 5/8, long-tube headers.
Pretty straight-forward deal that should make 1 hp per cubic inch pretty easily.