A tubular k frame with a power rack and pinion is a must as are disc brakes.
Okay, I'm with you on the disc brakes but why is a tubular K member any better? Are you under the impression that newer is always better? This is not always the case. How about the influx of cheap Chinese tools and reproduction car parts over the last 20 years ?
I won't try to force you into accepting my opinion but let me make a case as to why I think that a well prepared stock based suspension and steering system is a better way to go.
First, I will easily admit that the stock stuff is not on par with the handling quality that most new cars have. 40 years of advancements have to be worth something, right? The stock torsion bar suspension can be improved though. By making a few small changes and improvements, you can have a great handling car that retains OEM durability for about half the price of those $5000 tubular setups.
The addition of subframe connectors is a great upgrade. Taking it further, one should add gussets to the K member to stiffen up the steering box mounting area. I did both of these and also welded plates to the lower control arms. I used large anti sway bars, Poly bushings, Bilstein shocks and a Firm Feel stage 3 steering box with Fast Ratio arms. I figure I have less than $2300 in my front and rear suspension. My brakes are 12" discs up front from a Cordoba....Calipers and pads can be found at almost any NAPA store.
Mopar Action magazine had several articles on their 1969 Valiant dubbed "The Green Brick", a street car that they raced on road courses across the country. It had a stock based setup as I do and it blew away Corvettes, Porches and several cars that nobody every expected to lose...
Andy Finkbeiner built a 68 Valiant that was nicknamed "The Red Brick"....It too retained a stock based setup. Andy runs AR Engineering and supplies many parts to Mancini Racing for retail sale. Andy has written several tech articles for Mopar Muscle magazine as well as a few helpful tech books. He has stated that for most purposes, there is no advantage to running a aftermarket tubular K member suspension.
Then there is the issue of engineering: The setups that remove the torsion bars and use a coil over shock mounted in place of the shock are asking for failure. The stock Mopar arrangement was well thought out. Each section was built to carry a specific, limited load. The shock absorber mounts were designed to dampen suspension movement, not to support the weight of the car. Some companies do address this by implementing a reinforcing bar that runs from the firewall to the frame rail. This helps but isn't a nice looking addition to the engine bay.
These cars were designed around rather skinny 5 inch wide 14 inch diameter bias ply tires with limited grip. Today we have wider and taller radials that grip better than race tires of the 60s. The better grip of todays tires will induce flex and distortion in a stock unibody when the road gets curvy. The addition of frame connectors and reinforcements/gussets address this. Stiffen the platform and the suspension does not have to be as stiff for the car to handle better. When the whole car is flexible, the car is just another spring to bend and move.
Some choose the aftermarket setups to get better road feel. This is a great point. The stock steering boxes can be rebuilt and upgraded but to be fair, they are based on a design that dates back to 1957! My Firm Feel steering setup feels great in turns but still has some free play from the center outward....In other words, while driving straight ahead, the free play from center is more than a car or truck with a steering rack. Good news though...BORGESON has a fix for that. They offer a steering box setup that has a 14 to 1 ratio and has none of the slop or free play of the Mopar gear.
The aftermarket does make some shiny new stuff that looks nice. It is new and pretty but I wonder if they would hold up to the same stresses that the stock stuff can.
Good luck in any manner that you decide. It is best to be informed though before spending the money.
