So I've put this info out there a few times, the last time was a over a year ago so I'm sure some of the prices have changed. But the part numbers should be good.
The Hotchkis TVS is a great set up for handling. The only issues I have with it is that it doesn't include everything you need (no torsion bars, no shocks, etc) and it includes a few things that you really don't need (heim jointed UCA's, steering links), and it's pretty pricey.
For the price of the TVS, you can get components that will pretty much do everything the Hotchkis set up will do and take care of the "missing" parts...
1.06 (or bigger) Firm Feel torsion bars -------------$355
Tubular UCAs (PST, FFI, etc)------------------------$350
Adjustable strut rods (PST SR 14385)---------------$279
Solid tie rod sleeves (PST SAS 440S)----------------$49
LCA boxing plate (PST LCAPLTMOP621)-------------$14.50
Greasable LCA pins (FFI w bushings)----------------$135
Helwig tubular front sway bar 1 1/8 #55905 (73+ K)--$175
(#55917 for 67-72 K and large tires --- $263)
Solid rear 3/4 #6907--------------------------------$237
Mopar oval track springs
Zero arch- P4529414---------------------------------------------$232
1" arch- P4529415
Energy suspension 1" shackle bushings 2-2117G----$9
Bilstein RCD shocks(RCD-70-56663)------------------$410
Grand total on that is about $2,300, that's got a little extra built in depending on where you shop.
That's basically the entire set up that I run on my Duster. I didn't get all of those exact parts, my strut rods aren't from PST, I'm running Hotchkis Fox shocks, my UCA's are Magnumforce pieces I bought used and will get swapped out for my new SPC arms from BergmanAutoCraft, my torsion bars are 1.12", etc. But it will set you up with a great handling car. Don't get me wrong, the Hotchkis set up is VERY nice. They make quality parts. Probably a little lighter, definitely a little sexier. But, you'd still need torsion bars and shocks, and you might have ride height issues in the back (I run 121 lb AFCO's which are no longer available but almost identical to the mopar oval tracks). The other thing is that after running Hotchkis UCA's on my Challenger with heim joints, I wouldn't run heim joint UCA's again on the street. Mine wore out after 7k miles. Hotchkis replaced them at no cost and provided boots (great service!!!), but after another 7-8k miles I'm starting to notice some extra clicking coming out of the front end again. The heims would be fine on a track car or even a weekend car, but for a frequent driver you're going to be replacing the heims more often than I'd care to. Bushings work just fine and last much longer.
The only things I'd add other than what I've got listed above are subframe connecters, torque boxes, 17/18 rims with modern tires (BIG handling difference), and a good modern alignment, say -.5* up to -1* camber, +3 to +5 caster (manual to power), and about 1/16" toe in. None of that is included with the TVS either, but chassis stiffening is a very important part of improving handling on these cars.
As far as coilover conversions, you can handle just as well with torsion bars. The Hotchkis Challenger and Taxi are pulling close to 1g on the skidpad, which is on par with new performance cars and is actually pretty dependent on tire choice. The only advantages I see to the coilover conversions are header clearance and rack and pinion steering, but IMO neither are worth the conversion. They also require additional chassis stiffening IMO, because the chassis' of these cars were not designed to carry loads in all of the locations that they're applied by the coilovers.
