Stall speed depends a lot on power of the engine versus weight of the car, as well as cam specs (listed power band of the cam). Because its already a smaller diameter converter, it'll tend to stall to a higher rpm without modification. The shop that will be doing the work should have a better idea what you need if you give them the above info.
The stall converter may help it under normal driving conditions. The shift kit will do exactly the opposite, since the 7.25" does not like shocks to the system. The gearing change was a good idea, but I think you really want another axle than the 7.25".