What rpm stall converter should use?

Fill out and submit the "spec sheet " on the PTC website. Depending on rear gears and tire diameter they'll probably recommend their 9.5".

Your build is somewhat similar to mine. 5.9 Magnum, mid-size cam, Edelbrock 2.02 heads and 650 AVS, 1.03 torsion bars and HD Espo springs. 3.55's and 26" tires. I have their 9.5" in a 904.