A833 input shaft diameter

Have you tried pushing the bushing further in?
I have never seen a step on any of my A833 inputs, and mine is the same .750 all the way from front to back.
It is ~2.375 from the tip to the splines, the first 1/4 is beveled and the the last 1/4 is chamferred up to meet the splines. This leaves 1.75 of straight shaft. Add back the 1/4 " lead-in bevel and from tip to chamfer is a tic over 2". On mine, the bushing wear-line clearly ends at 1.75 from the tip, which being 1/2" from the splines.
Ergo you will need to take a trip to the lathe.

But there is something else wrong as indicated by the "about 1inch "statement. IMO your crank is not drilled deep enough, because your step is only 1/4 inch long. So even if you machine it off you could only gain that same 1/4 inch and only if that is the only problem. You need another 3/4 inch!
So I would see if that bushing will go further forward into the crank . In the factory crank there is a good sized step to stop the bushing.
Alternatively, you did install the clutch-disc with the flywheel-side, to the flywheel, right.

Many times the input shaft has to be cut off to fit automatic cranks and then we use the ball bearing pilot (sorry no PN) pressed into the TC register. This works real slick