Howdy LTDBob;
We had a chance to drive an '81 Mustang Coupe with a 3.3 and a 4spd OD, and we were stunned by its doggyness. It struggled to get over 4 grand on the dash tach. After a little investigation it appears that there are several factors limiting performance on the '79 -'82 200s, but the electronic feedback Holley model #1946 is a big part of the limitation. And an '83 is probably the most regulated of any.
My guess is that a Carter YF for a '75 - '79 FoMoCo 250, rated at 193 cfm. The other option might be the RBS Carter used on 250 engines from 1970 to about '74. The RBS is rated at 215 cfm.
Other factors contributing to poor performance on these engines is a very restricted exhaust, lower compression, built in distributor timing (this is a suspicsion), and incredibly tall gearing.
By the way, how is your gear change coming?
Adios, David