Re: 92 cougar xr-7 IRS swap into fox body Capri?
I saw a big block Chevy stuffed into a Metropolitan (remember those?) at a car show a few years ago. The point is, you can put anything into anything if you have the skills, time, and money.
We have fabricated cars "frame-up" over the years. My goal has always been to get total performance from a vehicle, not just to get it to run, and getting a modified car to handle right has always been difficult. So yes, you can make the IRS fit, but make sure to measure the factory mounts exactly, then duplicate the mounts and geometry exactly in the '82. Additionally, there are many ready cut suspension mounts available in fabricator catalogs available to NASCAR, off-road and circle track racers.
Obviously, your welding skills should be up to FAA standards if you are welding on suspension components and want the wheels to stay on the car.
Good luck! That sounds like a good project, tell us more!