What cam should I get?

I had the same setup as you but I had a automatic. I called Hughed cam and bought a cam with 208\214 duration at .050. You could get away with a little more with a 4 speed, but not much. Get a cam with the biggest lift you can get with the short duration. Lift is all good, unless the valve hits the piston. That should not be a problem with a low compression 273. In my opinion, Hughes makes the best cams for your engine. Bob