That's a 64/65 intake. It is possible the heads were machined causing some mis-match. I don't understand the difference in angle. How does the stock bolt angle compare to the Offy intake?
Pics 3 & 4 show the difference. It’s a little bit off between the 2. Enough to cause problems. That’s what is making me think it’s possibly for the latter engines.
I’m lost too! Lol