Ok, update time.
The Hypertech calibrator did its job quite well. The instructions leave a bit to be desired (like on WHERE to find the connection blocks, and not needing to pull them out), but things worked out. I made sure to get a good measurement of the tires up front. Plugging in that measurement got the speedometer calibrated just about perfectly; it matches up with Waze GPS-tracked speed.
The tires ... Ridge Grappler 35x11.50x20s. Making sure I got a solid measurement on the center line of the tire, they came out to be 33 9/16" at 45 PSI. Basically, I used a level at the tallest point on the tire, and measured to the bottom of the level. I need to check the tires for recommended inflation; for some reason, I'm thinking they're supposed to be at 50 PSI.
The shop did an excellent job, even provided me with a loaner while they worked on my vehicle.
I have run into one issue - the TPMS units in the tires. I kept my old wheels/tires, and the OEM TPMS were left in them. The new shoes got programmable aftermarket units, set to 433 MHz. The sensors in the wheel wells are having a helluva time picking them up. I'd put over 80 miles on them on the highway in an effort to get them working. I was up to 3, and was on my way to the shop to get a manual re-learn done when two of the three dropped. The shop tried wireless relearning without success. They tried the OBDII wired re-programming, which also failed. So, I ordered some more OEM units from Mopar. I'll get those put in and see if they help. If THAT doesn't work, then I'll be left with only one conclusion: the new wheels are presenting too much interference. More to come on this.