[DETON8R]

A few things to consider.
-What is your budget?
-What kind of performance are you really looking for?
-Are your performance expectations going to drive other upgrades, brakes/wheel wells/suspension adjustability?
-Are you going to do it yourself/pay someone to do it for you?
-And will a well designed 3-link or 4-link get you the same performance objective?
-What are the trade-offs you are willing to consider?
-What is your budget for wheels/tires?

I realize that you plan to do it yourself, however once your into the car, make sure you can make any repairs you start yourself. And some upgrades might be best left up to professionals with experience. I'm doing a lot of work myself, however some of the work will be done by professionals, like final suspension alignment, and critical welding. Make no mistake, I'm doing the vast majority of the grunt work and prep, but somebody else will be spending a few hours doing final alignment and welding.

Spend a bit more time looking at builds, search on IRS, C4 rear, Corvette rear, 3-link vs 4-link vs IRS.

Mini-tubs aren't required, but if the sheet metal in the car is being hacked and repaired anyway, it isn't a bad idea to have them installed because the cost might not be a factor with that much work. Any time you think about mini-tubs factor in the cost of wider wheels and tires.

There have been a few that put C4 Corvette rear ends into 1st gen Camaros, and there was a company, now gone, Wayne Due Enterprises, that made a bolt in/weld in bracket kit that integrated a C4 Vette rear into the existing 1st gen trunk floor and frame rails. You might be able to find someone that is duplicating the brackets, search some forums, I seem to recall that somebody has been making similar brackets.

Kugel, Heights, Blue Moon/Control Freak Suspensions, Scott's Hot Rods and Team321 make IRS kits, some ready too bolt /weld in, others not so much.

And there are customs out there too, Barry of Big Wheels.net had Pacific Fab in NorCal install a BMW IRS from a 7-series, and it has a cantilever shock set up in the trunk under the package try.