My 71 cuda has a mixture of XV motorsport level 1 kit, and Hotchkis parts that make up almost everything for the front and rear suspension and steering. I have the XV subframe connectors, radiator support, and US Cartool shock tower to firewall bracing. I have a FirmFeel steering box. I topped it all off with 18"wheels, and adjustable Afco shocks. I love my hydroboost brake system going to PBR calipers with 12.5" rotors.
Overall, the car drives great. Goes down the road comfortable. Not too stiff. I can feel the road. It really does feel like a modern car ride. The car is not very flexible and I can tell the suspension is doing its job of keeping the wheels on the ground. Chassis stiffening and sound deadner will prevent creaks and rattles. Steering feel is good during transitioning, with vague feed back from the tires to the steering wheel when at the limit of traction.
The car seems to have understeer, and that can be better tuned with the correct sway bars. Hotchkis rear bar is adjustable. The steering feed back is good when applying pressure on the wheel, but can still be vague when going straight, requiring a lot of corrections. There is some small amount of play in the steering. Any play it too much play in my opinion. The car seems to fall into sweeping corners and keeps going until I have to correct the steering to hold the line. To summarize, the steering is better than stock, but still requires frequent inputs to keep the car going straight, and requires corrections to have smooth corners. The one thing to make my car be much closer to perfect, would be precision steering feedback. I don't think we will ever get that with 45 year old technology. I may work on tightening my screw too as pointed out in this thread.