So I could only find about half of my documentation from the MP 5.7 crate I had. I was able to find only one, very clear picture of the manifold that shows that port. However, it the carb version of the manifold but should still help. There is a straight, pressed fit, nippled fitting in that port for a hose with in line PCV valve. I remember a similar, but 90 degree fitting in the one I had.
I think if it were my manifold, I would tap the hole and screw a 90 degree brass fitting in there and then put an in line PCP in there. Hope this helps.