get it going first and see what's what. We're changing parts and giving parts suggestions and know NOTHING about the heads (are they ported? 2.08's?), nor of the cam (????), nor of the compression (what pistons???), nor the converter.
For what it's worth, my brother had a '68 GTX with a single plane intake. the M50's wouldn't hook, and it would fish tail at 50 mph down the highway when floored.
Again, get it going and see. Maybe just a carb kit and the carb will work perfect.
P.S. - My opinion, that "vacuum secondary for the street, double pumper for the track" line is hogwash
