Nope, the shift point is determined by the valve body's calibration and the position of the TV cable. If your lighter car has it's gas pedal pressed to the firewall then the transmission is seeing the same position on it's TV arm and it will shift the same. The only difference is that you will reach that point much sooner with a lighter car.
My shift kit had a subkit for the tailshaft regulator with a stiffer spring to move the shift points higher. I would recommend something like that.
As for converters, dont use the stock one! Even if it is from a mark 6, I cannot see a factory car having more than a 2k stall, but more like 1200 or 1500. Get something like a tci streetfighter. Theyre cheap at $350 or so and stall at 3000 rpms which I consider to be the minimum for "pep" out of an AOD'ed combo. If in doubt...pick up a lightly used one on the forums, that wont break the bank at all. As a matter of fact, I have a "generic" 2k stall with about 3 months of light street driving on it that I would part with for $75 plus shipping if you are so interested.
Have fun!
