Exactly. You can do it a lot cheaper and still have a more adjustable suspension than what you get with the RMS or other coil over conversions.
My point is that the coil over conversions arejust modified MII suspension, there's nothing inherently better with them, it's not really any different than replacing the OE torsion bar suspension parts with the stuff I posted above. If you had a 1974 Mustang II and bought all tubular control arms, replaced the struts with coil overs and ran an aftermarket rack it would be the same thing on a different crossmember.
Design a custom crossmember, re-design the UCA's so they bolt onto an A-body and now you've got this View attachment 1715937459
Is that oversimplifying? Yes! Making an MII suspension bolt right onto an A-body requires a lot of thought and engineering, I'm not trying to take that away from RMS or HDK or anyone else making these conversions. But it is also not magic, and the final result is still based on that rusty, OE MII suspension in the first picture that looks a lot like the stuff everyone wants to replace on their A-body.
As for handling like an Audi, well yeah actually, you can do that with torsion bars. The Hotchkis Taxi, which is a 4-door Satellite, bested the 3 series BMW's that TireRack uses to test tires. Same driver, same tires, same track- the 4 door Satellite put down faster times with torsion bars. Two very different driving experiences no doubt, but, if you're looking at performance and lap times it can be done.
I've often wondered why these companies that build the aftermarket coil over/rack systems haven't changed the spindle/control arm design to that of the C5 or C6 Corvette. I'm pretty sure that's the design many of the big GM aftermarket suspension is designed after.