52Carl,
I hesitate to give advice on cutting the end off the input shaft, but the answer is yes. I have never done it. Many I have talked to have done it successfully. I have a junk S10 input shaft and I intend to cut it and see how well it would work.

What I say below is heresay, not first hand experience. I don't want to tell you things and then have you go and ruin an otherwise good transmission.

Tom Langdon sold an S10 T5 to a friend of mine and just before handing it over, he went and cut off about 3/4" from the end of the IS. So I guess Tom Langdon knows what he's doing. He also told my friend that he'd need to partially grind down some of the clutch disc inner splines to improve the travel. You see, the IS splines are not cut along the length of the shaft far enough for this application. Some people I've talked to have hand ground extra length to the IS splines.

A V8 Camaro and Astro van have the correct length IS and splines so no adapter plate is needed.

The S10 T5 has an IS that's too long. Some correct this with the adapter plate and just bolt it up that way.

Others cut and grind and get by without the adapter plate.

I intend to add write-ups on the process for each modification, but for now I need to keep working on finishing my truck build.