I've been ridiculously busy lately but this week I made some progress. I pulled the water pump housing and the part number is 3698468, which came on 73-78 Mopar big blocks. I was kind of hoping that it had an after market housing that was the culprit but that doesn't seem to be the case. The big ports were clear/clean.

I pulled the heads and the head gaskets are in good shape with no signs of leaks. My 906 heads are pretty much junk. Most valves seats are sunken; the valves are all cut at different lengths, and I have a couple guides that are working themselves out. The heads "smell hot". I know that's unscientific but you know what I mean. I drained the oil for the first time. The oil only has about 20 miles on it but I wanted to see what was in the oil. It was surprisingly clean but smelled rich.