AD, thanks for linking my site. Always better when someone else does it, I don't like blowing my own horn.

There sure is a lot of S-10 swap interest lately, huh?
I've seen this swap done a few times. At the local big car show a few years ago, there was a buildup done over the weekend - they installed a prewar pickup onto the S-10 chassis. The thing was all built previously, looked like they took it apart to paint it and reassembled at the show. It was cool to see but it was a 2WD chassis without the torsion bar suspension. And I remember that they solid-mounted the body to the chassis.
Another one I saw had the steering box sticking out of a hole in the front fender. Looked like it was an 'oops' not expected until the last minute and it just barely didn't clear the fender so they cut a hole for it.
There was another guy I was in contact with that did this swap - '90 S-10 4WD chassis, '38 Chevy. He mentioned he needed another 4.5" in order to fit the rad in. I think he wound up putting the rad behind the cab and apparently it worked great. He mounted the cab up a little higher than most so I don't know if he had steering box clearance problems.
Seems to me that there isn't 4.5" to move the engine back without modifying the torsion bar mount. I need to move mine 4" at some point and it'll be tight with that. But as long as the modifications to the torsion bar mount are solid, it should be easy enough. Moving the trans mount should be straight forward (or straight backwards in this case

), I'm pretty sure there's room to slide it back enough before running into the torsion bar mount. Here's the best pic I could find of that area:
Hope this helps.