OK, I have just done a test fit, as the bees have gone to bed for the night. It looks like it can be done, but there is one hurdle that would have to be done to make it work, that I don't quite know if there would be a consequence to. The outlet on the top of the S13 radiator is on the passenger side all the way at the end. That is opposite to the Supra, but I'm sure you could make some sort of hose work, but it would have to do a complete 180 to mate up with the thermostat housing. Or, possibly a hose could come straight off and just do a 90, but my shell has no motor to see exactly where the thermostat housing would be.
As far as fitting, it seems to fit the hole better than the Supra radiator. You would have to do something as far as the lower posts. Both posts sit on the outside edge of our stock holes. I think you could actually just weld a small half loop onto the stock brackets. As it is, the radiator sits on top of our brackets just fine, and height is perfect. The S13 radiator also tapers off at the top on the passenger side a little before where the stock upper brackets go. It shouldn't be too hard to drill and tap a new hole a couple of inches over for that.
I left my camera at work today, so I will have to take some pictures tomorrow.