Remove the rear main bearing cap and loosen the bolts on the other three caps at least 3-4 turns. The crankshaft should drop about 1/8" or so, leaving plenty or room to install either seal you choose to use. I don't think I've ever had to remove a transmission to change a rear main seal- - - -there's plenty of wobble in the input shaft to let the crank drop a little without going to that extreme. I'm partial to the rope seal- - -it seems to work better, especially if there's any roughness or a groove worn into the crankshaft hub. The only really effective way to make the back end totally dry is to machine the back of the block for a full-circle lip seal like the Ford V8 Diesels use.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!