2nd gen Camaro rear suspension options

[SPG]

So I've done a lot of research on this subject and it feels like every other week I change my mind on what I want to do with the rear end of my car, so I'll lay out my plans.

Right now I plan to put an lt4 (gen V) engine in the front of my 1975 camaro, modify the subframe with global wests "true" coilover set up, upper and lower arms, front sway bar, put a quicker ratio steering box in the front, rebuild the steering with new parts, 12.9" wilwood brakes (I hope) and viking shocks....basically the global west front catalog.

I want to autocross my car, I don't know how often I plan on doing it as I have never done it, but it looks really enjoyable so I'd like to do it a lot. But the primary purpose of this car will be to just drive it on the street.

Now here is where things get controversial and where all my problems arise, on the street I want to use 15" rims with big meaty tires for that old school look at near stock height (probably lowered maybe 1/2 or 1"). When I take it on the road course I plan on putting bigger rims (17 or 18 not sure yet) and lowering the car so it can perform better. In my head that makes sense, but we don't live in a perfect world and has brought up a lot of challenges as you can probably imagine.



So here is where I stand, the rear suspension has a lot of colorful options for a 2nd gen camaro, you have leafs, torque arm, 4 link, and an IRS. Maybe more that I'm not aware of.

1. With leaf springs you can get sway bars, traction bars from umi, global west has some special spherical bearing in their cat 5 system, list goes on, lots of options. But my problem with leafs is that you're kind of stuck with what you get, if you're not happy with the height there is very little you can do about it aside from move the shackle that the leaf connects to. Leafs aren't really out of the picture, but the lack of adjustability makes me not really want to go towards it.
2. Next option is a torque arm, I've seen one from BMR and Chris Alston's Chassisworks but I can't really find anyone using them? maybe I'm just looking in the wrong places. Honestly I just want to know if they're good or not as they seem to be my best option for a solid axle type set up, I know they were used in 3rd and 4th gen camaros so I assume they have to be decent, but no one really seems to talk about it. Only "issue" with these set ups is that I can't change what rear end I use (start with my 10 bolt and then upgrade to a ford 9") making point of entry more expensive. Don't get me wrong, it would happen eventually, just means it will take longer for my car to be a roller again.
3. Next is a 4 link, which DSE and ridetech seem to be the most popular. People seem to talk bad about ridetech, are they actually a poor performer? or is it just bias. I know DSE makes some great products that are "race" proven but my issue with them is that it requires me to completely mutilate the rear of my car, which I really don't want to do. I'm more than capable but it's something I'd like to avoid as much as possible. I know the ridetech 4 link requires you to cut two giant ovals in the rear seat, but thats a much easier pill to swallow than cutting giant holes in your frame rails. I think chassisworks also makes something, but again, don't really see anyone talk about it.
4. Last one, and the hardest for me to get any info on is IRS. The only two that I could find is art morrison and heidts. I know art morrison is fantastic proven set up, but they have 2 "flaws". First is it requires me to to always use 17" rims (ya I know it's a stupid reason) and the other is it requires me to completely "destroy" the rear end of my car...I don't even know if you can keep the rear seats after the install. It's most certainly way too race car and far beyond what I want this car to be. The other is Heidts, I can find a lot of marketing on it but I can't find anyone using it. It looks nice, some people have commented that the inboard brakes is concerning, and some have said it's "show car" suspension which may be true, it's also expensive so if it's garbage I don't really want it. I have found 2 people putting it in a first gen camaro, one hasn't driven it yet, and the other I can't get hold of to get their opinion so I'm kind of at a loss. The other thing about that system is that it forces my car down 2" and it looks like I have to dump the exhaust right before the dif, which I don't think I want to do. I can probably survive the drop but that kind of circles back to the leaf spring issue where I lack the adjustability that I want.

So thats where I stand, I have 4 options presented to me, all of which require some sort of compromise, and I have no idea what I should even do. My arbitrary requirements makes this more difficult than it probably needs to be. If I go with option 1-3 I think I want to get a ford 9" full floater axle from moser as from my understanding they're stronger, and safer than my stock GM 10 bolt. Right now I'm leaning more towards the BMR set up. But I also want the heidts system...but heidts is a very expensive solution to something that might not be worth it.

Anyways, would love everyone's opinions on these various setups, preferably if you have used any of these.