bubbles coming out of my radiator

i have an 85 corolla that i was given and im trying to revive the engine. after a tune up and cleaning and rebuilding the carb i got it to run, but i noticed a problem with the cooling system. when you run the engine with the cap off it has small bubbles and foam that eventually overflows out of the fill cap. i know that this is most likely combustion gasses escaping through a blown head gasket or a cracked head. the only thing im a little confused about is that the compression reads great and it doesnt overheat or heat up quickly. it also doesnt build up enough pressure in the system to pop open the radiator cap. the car sat for 2 years before i got it, but it was still topped off on all its fluids. it has a little bit of a miss at idle, but thats it. compression is 195 197 197 197. its almost perfect. it burns no oil and the engine has ABSOLUTELY NO LEASK ANYWHERE on the outside. there is 118,000 miles on the car. has anyone had this problem before? im just trying to find out if its the head or the head gasket. it will be the deciding factor if i keep the car or not. thanks for the help!!!

Check the water pump