I would try to make cheater screw-in studs with the hex machined off, or maybe you can find some that are already made that way. You can mount the gudeplates with two bolts like they are for press-in studs.
Maybe you can convince them that most Pontiac engines came with screw-in studs and therefore should be allowed.
Most tracks are looking for more variety in engine makes, so you may be able to get them to bend the rules a bit for Pontiacs.
Too bad it's a claimer, #48 heads would work well.
Use ARP rod bolts instead of the factory ones and get the rods resized. Low tension rings should be OK since oil consumption is not a concern and they'll help reduce friction. You can mildly port the heads if the ported areas are shot blasted to match the original casting roughness.
Any rules against cutting the backsides of the valves or rounding off sharp edges?
Do the rules require a hydraulic cam?
What 2bbls are allowed? I think some of the Rochester 2bbls are good. I've heard some cheaters use the power brake vacuum port to suck in extra mixture from the gas tank fumes. Don't know if it's worthwhile though.
Try to find some rusted out/cracked Ram Air manifolds. They come up for sale now and then. Maybe R.A.R.E. has some rejects they would sell you cheap.
I don't think the '73-'74 EGR Intake manifolds are restrictive.
http://fiedlerh.home.att.net/