New to site, new to Mopar overheating issues

The casting # is
2780930 340-3 – 1968-1973, 340 LA-series small-block, Not T/A or AAR

Yes unfortunately the guy I bought it from know nothing about the car, I contacted the guy he bought it from (another dealer) and he doesn't know anything either. Honestly, it's a good car, but I missed several things while looking it over. Missing kick down cable/linkage, dash lights don't work, radio, heater didn't work (fixed heater), they had the transmission fluid way too full, and obviously the over heating issue. Granted some of the stuff you can't spot or don't think to look. Happy with the car just kind of pissed the guy wasn't fully truthful.
Hang around here long enough and you will have it all fixed and working good. Pretty car by the way.