Joe,
This is all guesstimating on my part as I have never done this swap. If all the clearances were snug before, then your analogy makes sense.
Does the original 1-3/4" have a recessed hub in back. If this is true then it doesn't sit further out on the crank flange and no modifications would be necessary.
If you spend some time with a tape measure, you should be able to make a cartoon that shows the relationship of every component from the face of the bellhousing, which is the front of the tranny, to the face of the crank flange, which is the back of the flywheel.
Sitting at the kitchen table with a cup of coffee, you should be able to dimension the drawing and see any interferences that would cause your problem.
I may be oversimplifying the problem.
Stuart
