With the 700 trans, you will hardly notice any difference between 3.73 and 3.90 gears. The lower first gear will give you plenty of pick up while the overdrive will make either gear pretty nice on the highway. That being said, most camshafts wouldn't notice much difference either.
What cam you pick really depends on what you want to do with the car. Going by the fact that you have the single plane intake, you probably want a longer duration cam to match in which case a 2500+rpm converter may suit you well. If you want this build to see lots of street cruising and less full throttle blasts, get a somewhat shorter cam and a 2000-2500rpm converter. With the 700 trans though, get a lockup converter. This will pretty much nullify the overheating issue.
Also on cam selection... what kind do you want to run? Hydraulic? Solid? A roller of some sort? If you are going hydraulic and want to run a 2000-2500rpm converter, look into something like Comp's XE274 I would think. If you want more cam, go with the XE284, but you may need a looser (higher stall speed) converter.
Also keep in mind vacuum with your cam if you are running power accessories. If you run a really big cam, you will need a vacuum resevoir or possibly a pump.