Can you help id this slant six..!?

I'm looking for a 66 225 if you decide not to use it.

If the consensus is that it will not work in this car—all you need to do is come get it. I’ll help load. It’s all the conflicting info I have that perplexes me. The 66 cast date—the 67 build date—and that I was told it came from a 68!!!

It’s clean and nearly complete—no alt or ps—everything else.