225,slant six radiator

Update: it was the radiator! Removed water pump, then I flushed the block. They were ok so I took the radiator to a real old school radiator shop close by- 85 bucks later and the old radiator is clean and new again. My radiator guy said it was plugged full of gunk and he also soldered a couple of small leaks. Now I just have to put all back together. Thanks to all who offered advice and knowledge.