Help w/B&M Converter 2400 Holeshot

Ive used a few including tcis and they never stalled where they were advertised,for me they were always too tight and stalled a few hundred lower than advertised.After a few phone calls I found out that they were all remanufactured convertors and the stalls were based on a mild chev 350 in a medium weight car-not sure how that specs out across the board?.I doesnt seem like a very technical way of doing things and this was straight from their convertor tech.