There is a (modulator valve?) pressure setting that, as far as I know, affects the shift points. Have you tried the search function on this site yet? There could also be relevant information here:
http://www.sl113.org/articles/default.aspThe ignition timing also affects the vacuum that helps to regulate the transmission shift points, but I am assuming the ignition was not altered when the transmission was swapped out, so 'technically speaking' (that's a pun I believe) it should not be a factor in your situation?
Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic