If you're referring to your 1977 engine, it has a 2-piece rear main seal. You can replace it by removing just the rear main bearing cap. Here is a discussion about doing this:

https://www.ford-trucks.com/forums/6...main-seal.html

There used to be a company that sold a mesh tube device, commonly referred to as a "Chinese Finger Trap", that was designed to draw in the new half-seal without damaging it once you removed the old one. You load the new half-seal into the mesh tube, pull both ends of the tube so it tightens around the seal, and thread one end of the tube through the groove in the block. Then you can pull the new seal through by keeping the tube tight. When it's in, you release the back end of the tube, and you can pull it off of the seal, and you can make final adjustments to its position.

I didn't use this device, as I was able to lube up both the new seal and the groove enough to push the seal in by hand.

If your engine is newer than 1982, it has the one-piece seal, and you can change it without dropping the oil pan or rear main bearing. But you do have to get the transmission out of the way, which apparently you already have. You basically destroy the old seal by screwing coarse thread screws into it and pulling it out.

If you had to loosen the other crank bolts to slightly drop the crank shaft, there's probably enough slop in the timing chain that it will not interfere with the small amount that you have to drop the crank.

As for tightening the bearings back, the only one you have to be careful is the rear main cap, as that's the only one you have to remove, and the rest were loosened but left in-place. Make sure that it is properly lined up when you install it. Again, this would be for the two-piece rear main seal.