So I just picked up an 84 camaro with a 350 from an old truck and trying to get it home it seems like the cooling system built up enough pressure to blow out the heater core and the radiator together and now it pisses anti-freeze into the car and all over the ground.

Could this be because the hose to the overflow tank is plugged and isn't the radiator cap supposed to vent excess pressure?

 

it does but through the overflow so if that is cracked excessive pressure might build up. that could be your problem. but you may have a headgasket problem.