3000 Stall too high?

I am getting ready to pull the trigger on a converter for my fish / (340 now, 416 next),/ 904 / 3.91. Right now the 340 leaves the line at about 2200 and seems to stall about there on the street. new to this converter stuff. The car runs about 2200 on the street at what I think is a back country road speed limit of 45 in 3rd (no speedo). Would a higher stall "disconnect" the engine at that RPM and make the engine "float"? I need the tach to judge speed. Might need a GPS or put back in a speedo.