If you scroll back to the post where I link the ratio calculator, you can see roughly what the engine revs vs. the road speed is. Terminology I am using is that the "final drive" is the gearing in the differential(s), meaning it's the last or final gear-set power goes through before the wheels.
For 65MPH, unlocked TC, engine rpms would be (roughly):
With 700r4, 4.56 final, and 33" tires = 2232RPM
With 700r4, 4.10 final, and 33's = 2007
With 700r4, 3.73 final, and 33's = 1826
With 700r4, 3.42 final, and 33's = 1674
With 700r4, 3.08 final, and 33's = 1508
For 65MPH, locked TC:
With 700r4, 4.56 final, and 33" tires = 2113RPM
With 700r4, 4.10 final, and 33's = 1899
With 700r4, 3.73 final, and 33's = 1728
With 700r4, 3.42 final, and 33's = 1584
With 700r4, 3.08 final, and 33's = 1427
With the 6.2, the power band is from about 1600-2000RPM (and the efficiency band is roughly 1600-1800) . My suggestion of doing 3.73 is based on these numbers putting your truck in the lower end of the power band with a TC locked at 65, and the approximate middle when unlocked to allow for acceleration. You are still in the power band this way should you drive at 75 or 80 on some road where that is legal (i.e. the salt flats in Utah on highway 80). 3.42 might be too low as with the TC locked up, the cruise speed would put the engine below it's power band by almost 100RPM. 4.10's would be too short a gear as with the TC unlocked, you'd be already at the upper limit of the power band at 65, leaving less power for urgent acceleration to 70MPH.
Thus I stand by my opinion (and remember it's just that) being that 3.73 finals with a lockup TC in a 700R4 on 33" rubber is basically ideal for this engine for on-highway use.
LATE NOTE: For historical reference, the original TH400 3-speed with 3.08 final and 31's required the engine to spin at ~1950RPM at 55MPH (just inside the limit of the power band) - given that the federal highway speed limit was right about there in the '80s, and there was little reason to expect a truck to see anything vaguely resembling 80MPH, the gearing is just right for that set of engineering constraints. The D10 Blazer was also not expected to tow anything of significant weight with a towing limit of 3,000lbs total (3/4 ton - including the actual trailer's weight).