When seating the 4HP22 torque converter to an M30 535ia engine, I turned the TC by hand until it slipped into what seemed to be proper place. With the tranny in neutral, it would spin on its shaft. No leakage.

I placed the TC so one of its 3 nut fittings would be opposite the access hole (right side, lower) on the engine block.

Then, bolted the engine to the tranny. Engine snugged up against the tranny bell housing flange in symmetric fashion (flange surfaces parallel), with only a slight gap. So far, so good, apparently, and flange bolts went in smoothly.

Then, as engine was set at TDC, I noticed that although the engine access hole and one of the 3 the torque converter nuts may have been aligned, none of the flywheel holes were in the same alignment due to TDC engine placement. (gotta have TC nut, flywheel hole, and access hole all lined up to insert the bolt)

Turned the engine, thinking the flywheel triangle plate should be slightly and sufficiently clear of the TC nut fittings to allow non-binding rotation. It wasn't, but instead was binding. So, I had to slacken the bell housing flange bolts to create a small (~2-3mm) gap between bellhousing and engine block, thus allowing the flywheel triangle plate to clear the TC nut fittings for alignment. Then installed 3 flywheel/TC bolts, then tightened the bellhousing/engine flange bolts.

Having read horror stories of improperly seated TCs that destroy transmissions on startup, I'm worried. Various sources say there should be some (~2mm) end float between the properly seated TC and the flywheel triangle plate, lest aft pressure from the triangle plate damage the transmission pump or seals. The TC seemed properly seated, but before I start this sucker up, it seems prudent to ask for insight and advice.

Your thoughts on how to proceed?

Is there any way to check for proper TC seating without removing the engine from the car?