Small world, I just saw your posts on the burb 2500 fb page. You've got the newer rear window with the little spoiler on yours too, been looking for one of those since all my defrost traces are fried anyway.
I like the color matched grille, been considering either doing that, or leaving the center strip chrome and painting the rest.
Which torque converter does yours have in it? GM used two different converters in these trucks, some have a ~2000 rpm ish stall speed and others have closer to a 2400 rpm stall speed. Might be a happy medium vs. going up to a 3k stall? My cammed 8.1 is set up to lock the converter at WOT in second and shifts and tows mostly locked up. Stock converter clutch with calibration changes has been handling it fine, though boost may be a different story. The stock tow haul mode generally has this same behavior though. Mine has 3.73 gears and the higher stall speed OEM converter, which definitely helps with getting out of the hole.
1.75" is what I went with for rear spacers. This is the only pic I have right now that sort of shows the wheels, it's almost perfect if not a little too wide. If I did it again, I would probably do 1.5" spacers. On 245 tires right now and the rears are pretty well flush with the flares/mudflap outer edges. I got mine from Bora, since I wanted them to be hubcentric. I'll have to see if I can find a better pic.