One more question. Did you check the clearance between the rubber seal and the crankshaft end piece? I usually do that when I have the block on the stand upside down. I use a common piece of copy paper about 1/2 inch wide. Lift up the crank (no caps on it yet), set the paper in across the rubber seal about 1/2 inch and set the crank down. Then try to slip the piece of paper out the back end. It ought to be tight...the copy paper is .004" thick. If you have something less thick (maybe .001" shim stock) you can use that. At any rate even .001" thickness should have perceptible resistance. You don't want too much but you want some. Hard to put into words.
Yeah, I have those memories about laying transmissions on my chest and scooting out from under, also. Plus some others that have nothing to do with engines, transmissions, etc.
Good luck. I'll be curious about what you find, Mike.