New engine issues

Aj I have no idea what you are talking about ? Transfer slots? I haven't been able to drive the truck yet just starting it up and letting it run. The truck has 727 auto with stock converter racing shift kit and the rear is 8-1/4 with sure grip and 3:55 gears. Why do I need a 3000 stall converter? The pistons are aftermarket flat tops and is a little above stock = higher then 8.5:1