I will take a crack at this one. :-)

I would think a big block car should have a 26" radiator and not a 22" which would be correct for SB or /6. This would be the first thing I would upgrade to address your cooling issue.

I have heard mostly negative things about using pusher fans from "they do little to nothing" to "they hurt cooling". I have heard some say they can actually obstruct airflow through the radiator when you are cruising because they sit in front of it. At idle, it might help some, but I would not pursue this course of action. In addition, you will most likely have to upgrade the charging system to handle the extra current draw since you will want to run that fan @ idle where your alternator output is at its lowest.

Also, make sure your fan shoud is well-fitted (better have one). If I were you, I'd see about going to the larger radiator first. I think a 22" radiator with a BB is a little tiny.