Hi. I don't have a torque wrench that goes down to 3-4 ft lbs however I did a little test to estimate the torque required to spin the tailshaft.
Let me start by saying that my OD has not been rebuilt but came from a donor car with about 50,000 miles on it. It will not spin after force has been released which I would not expect anyway. There is a lot of friction in there. By the way you did not indicate if the OD was attached to the gearbox when you were testing it. If not, none of what follows means anything.
First I tested it in neutral which should give the lowest readings. I clamped an 18 oz vise grip to the tailshaft knob and the weight of the vise grip was enough to start it turning. Measured 6" from jaw to end. Assuming that the vise grip weight is uniformly distributed then the 18 oz at 3" would result in .28 ft-lbs. In reverse I had to clamp it on the very edge of the flange so the calculation was 18 oz at 1 ft so that the calculation results in .56 ft-lbs. Both measurements far below what you are reporting.
On the other issue of spinning the tranny via the input shaft, I get your all concerns, unfortunately (my wife always complains about my lack of impulse control) I already did it. I examined the input shaft just now and it doesn't have any scars from the operation but I won't do it again (I promise, ha-ha). I still need to borrow trans pressure guages from my friend.
One last question for general discussion. The OD manual that I downloaded (
https://www.tonydrews.com/Overdrive/A-type OD manual.pdf) refers to the correct positioning of the valve control lever. That is when the solenoid is actuated, the 3/16" hole on the other side has to line up with the hole on the OD body. Mine does not as the lever goes past the body hole. Should I readjust this?