I'm guilty of my own pet-peeve with a classic "Help Me" but providing no data. OEM SS coils on FTSS, babied lo-miler with FE1 on the right.
-It'll be my driver for the next 15 years, just as the FTSS was for the past 16. My official designated garage queen is the '96 Imp. There's a 6-speed laying next to it for someday, but I digress.
-The new white one (I'm liking the new Lincoln tanclay for repaint) will be the worker.
-Goal for this one will be approaching the handling of a nice new S-Maybach, - but for $170,000 less. You know nothing unreasonable.
Seriously, the car as it sets is a clean 52,XXXmile beaut, and short of an IRS and some one-off R&P steering I'm hunting for what you referenced as critical in correctly matching coils-shocks-bushings-bars.
The FTSS took 2 years to get right using cobbled together and repeat tries at used pieces off the Impala combined with eventually just stiff Bilsteins and some aftermarket LCAs. I'd prefer to do it right with the correctly matched set of new (retail priced) stuff - but only once.
My last FWB gave me the following:
-intersection turns that felt like autocrossing, and could never get the tires to squeal even trying hard
-very gratifying straightline road feel
-flattened "non-overcorrection-requiring" maneuvering between lanes
-got rid of the pushing, plenty of oversteer
I'd like to replicate as much of that as possible. Not a tall order. Just sacked out SS coils all around gave a good ht/rake (right at 2" drop in front with the old gray one and the new white one next to each other.
I hope that helps, though most of the input is qualitative. You may end up recommending just matching some simple samebrand coils, bars and LCAs and call it a day. But there may be some German skunkworks stuff going under the newest Audis or AMGs too that you know about. lol
Other points to entertain:
1.If going after boxing the frame - but without lifting the body - where would it be for you? The F- front brace is a given, welded of course. I'll even be looking into jounce bars of some sort. Anything that stiffens things for turns but without locking down straightline comfort to the point of feeling like an old Vette.
2.If compromising comfort a bit and allowing one place - and one place only - for poly bushings - where would you do them? I bet you say A-arms eh.
3.For any return on actual performance or ride comfort (and especially considering the cost and work) do AirRide systems belong on anything other than lo-riders and tractor trailers?
I read decades ago the famous Cadillac Ride was their engineering really wimpy spring rates together with stiff shocks (well as stiff as blu-hairs could tolerate and still not feel the road at all). You make mention of keeping rates low which is exactly my reasoning - but without your scientifical experience of course. The front simply must drop - almost 2" I'd say. Some for stance, but mostly for road viewing ahead. The difference between FTSS and this new one is unnerving, like between seeing everything v. the feeling I'm going to run over a little kid I can't see.
The only thing pretty much set at this point will be some sort of 17-18" 8 1/2" wheels, but with at least the same or greater rolling ht tires as stock. I saw something on an Infiniti SUV that looked great. I ran simple SS wheels with 255 55's before, and that provided plenty wide pattern and decent sidewall cushion.
Finally, I'll have to do NavyLifer's rear discs AGAIN, but that's not really susp./chassis.
Thanks for playing along. I hope this makes up for the last post. haha