I chopped the top on my 88 S-10 about 4 1/2 inches,and I dont think you would want to go too much more than that. I used honda bucket seats,and bolted them directly to the floor.I am a little under 6' tall and it is a little tight inside.I also built a cage in it,so it is even tighter. I had the windshield cut by a local glass shop.They charged my $125.to remove the windshield from the truck,cut it down and put it in a box in the bed.drove home without a windshield,a little drafty,but not a great distance.I bought my tempered side glass fron a company that is no longer in business. My rear window is plexiglass,because the roll cage rear bars run through it.Most of the chopped S-10 s I have seen had plexi side windows,but they are not legal for inspection in most states.
I see you are in Ohio,so inspection is not a problem,lucky you