TP sensor voltage should be right at .95-.98v closed and 5v at WOT. You can check it with a VOM with the engine off and key on. Use a straight pin into the signal wire to get the reading.
Here's a link that will help:
http://www.muscularmustangs.com/tps.php
Testing info for modulars is at the bottom. A quick google search returns lots of pages with details specific to adjusting the TPS on modulars. I have a spare TPS laying around. If you would like to have it for a backup in case yours is hosed PM me and we'll work out the shipping. It's from an FRPP 70mm TB.
As for the shift scheduling, since you're using the Xcal to adjust the shifts, I'm going to assume that you're not using the Advantage software to make the base tunes. I don't know what base tune you're using so it's hard to make any good guesses to a solution. I would suggest calling up Rick at Amazon Racing and having him set you up with a tune that's optimized for the increased tq. If you've had a chance to get it on a dyno I'd send him the graph so he'll understand the nature of the tq curve.