Need help from a experienced TPI guy

Hi, I got a real problem that I can't figure out. I've got a 66 nova with an 87 vette TPI motor in it. I rewired it with a painless wiring kit. I haven't been able to get it to start. I put a timing light on it and only four out of eight cylinders are firing. The computer is on, the fuel pump is running, there is enough fuel pressure, but for some reason I'm not getting full spark on all eight cylinders. I replaced the cap and rotor, all the wires are brand new, plugs are new, is there something I'm missing? Any help would be greatly appreciated. This problem has managed to stump my dad, my auto shop teacher, the guy at NAPA, and pretty much anyone I've asked. I'm just a twenty year old guy trying to get his hot rod on the road, SOMEONE PLEASE HELP ME.