215 overheating issue

Hello everyone. For the past 17 years my family has owned a 1963 OLdsmobile f-85 station wagon. I know that they did not make a turbocharged wagon that year (i wish they had), but my car did have the high po 215. Anyway we traded that motor for a rebuilt 215 buick motor that was decently built up. That shot a push rod out about a year and a half ago, and locked the motor up (motors fine now turns out). I bought the car from my dad then, and got a 2 barrel 215 off of ebay for a good price. The motor is now in the car, but my problem is that after about 10 minutes of idling the motor starts to overheat. At first we thought it was a stuck thermostat, so we took that out, no luck. When the motor went in we put a fresh fuel pump on it. The one thing I did change on the motor before it went in that was sort of major was putting the old 4 barrel intake manifold on it. It still has the two barrel heads on it, and I have 4 barrel heads in the garage, and I was wondering if the water jackets are different on the two heads, or if its another issue. I know it sounds awful to swap a buick 215 into a high po wagon, but the car is also a traditional custom. It doesn’t have door handles anymore, its got jaguar headlights, and a host of other mods. Oh yeah, its a factory ac car as well. One day I would love to get the turbocharger setup for it.