This is a little backwards, but my shortblock is for a 76 2wd, the $30 20r i have is out of a 4x4, i'll probably just yank the pickup tube out of the parts 20r since i'm pulling the oil pan to put on my shortblock... as long as that will work!
I don't know a whole lot about the older engines, But I would like to mention that you should clean out that oil pickup VERY well. Because its out of a truck with a rod knok, who knows what nasties may be caught in there.