Sorry, you're right. I forgot that the speedcal are only set up to work with up to '98 Automatics. Looks like you're going to have to settle with changing the speedo gear, or spring for a hand held programmer.
By "Speedcal", he's referring to a particular piece of hardware itself, not a "speedometer calibration" flashed onto his computer like you're suggesting.....although that would likely be his best bet.
Get 4.10s unless a blower is coming soon. A speedo gear would be a bad choice for the auto anyway. The shift pattern/points would be all screwed up without a chip/tuner.