Hey Christopher --- sounds like you are pretty much spot on. The "sweet spot" referred to is valid when on level ground at highway speed. Hit a hill and yes, gonna have to downshift to avoid lugging. The spot on my 4 banger is 1800 and that is what I geared and tired it for at 63-65. I am confident it will run higher but hoping to get max mpg's and service life by staying within the numbers.
Cannot comment on adjusting the trans but with your skill you can probably optimize it with precision. Me?...with an all mech engine and cable shifter, I'll just have to listen try to shift accordingly.
BTW...have you been monitoring your MPG's? How are they looking?
your trans is very much electronic and adjustable, the shift points can be adjusted to respond more or less actively to your go-pedal position. the mechanical shifter is just used to select a range. so if at spme point in a trip you know you are going up and down a bunch of hills where you always need 5th or even 4th to cfrest.. theres no reason to have it keep going back to 6th for 5 seconds just so you can stomp it back down to 4th.. so in my case when I get in any hills I go to a range with 5th being the max.. I can pull my shifter handle from (D) to D(4) and disable all overdrive if im going up and down steep stuff..
your pedal position is ultimately like an instantaneous range shifter.. typically you set that up so if you have it floored then its going to shift flat out at close to your self determined engine redline.. personal preference.. with the ratios of my gears, my engine peaks at 2300 (Horsepower).. but the turbo spools up alot till about 2550 - 2600. redline is 2800 unloaded. I shift flat-out-floored at close to that 2600.. when I hit the next gear im right in the middle of the power band and the turbo is spooled so the amount of 'Go' is good.. obviously if I punch it im looking for 'GO' not economy..
when im at 75-99% throttle I tend to favor the lower gears as im still looking for a decent amount of go. but I wont shift at near redlines.. the thought is that at those throttle positions im either still trying to accelerate or on a bit of an incline sp keep my gear lower longer and be more responsive at downshifting..
its a progression. I dont have the bus out today (school busses like the garage better when its snowy), or id post a pic of the shift graph for one of mny gears.. its a perogressive curve.. and a work in progress.. I still drive around and think "man I wish it would shift a little sooner.." so I make the change.
at lower throttle positions I try to get into the higher gears quickly and keep my RPMS in those ranges we talked for best torque.. It will run at very light throttles in that 1000-1200 RPM range. but any push on the go pedal at all and im going to pull it down..
with yours, your allison guy will have put a base program on it based on the specs you gave them.. and simply you'll just have to drive the bus around in various situations and either his base program works for you, or you need to have it tweaked.. you wont know till you take it oput and drive it.. and that first shakedown drive or two it will shift like Crap.. im sure you watched my video of my first shakedown after trans installation.. it was flaring, bucking, sensors were reading wierd.. but after an hour or two in and the next day it had gotten 200% better..
my economy at 65 MPH has gone from 8-10 to solid 11-13. with the current trans.. drive it at 60 and it sees 12-14..
-Christopher
Sounds like you have a Henderson, KY Dana rear axle. Heck, I might have hauled your axle to the factory back then since Walt's Drive-A-Way had a contract with Thomas from Henderson, KY to their Carolina factory..... 
