The downside of 'outside-the-box' builds is that you'll be a little limited on available performance parts. That does not mean that you can't put together a great package.
It sounds like you're looking for a versatile solution, so I'll give you a couple of different options for the front
suspension.
Front Bolt-On Coil-Over
The cool thing about this option is that it offers full coil-over system benefits of a spring rate selection, spring load adjustment, and adjustable shock valving, AND can be used with OEM or aftermarket upper arms. A great option if you're limited on budget or taking smaller steps towards converting the front
suspension.
Front Coil-Over Conversion System
This will get you to your performance goals for the front
suspension. It features the same shock and spring benefits of the other coil-over system, but with an improved motion ratio, which allows the shock and spring to work more effectively. The
control arms and strut rods feature pivot-ball mechanisms or teflon-line rod ends. This is primarily what makes the most noticeable difference in perceived vehicle handling.
Steering
So here's where choosing a '72 begins to limit your product selection. I do not have a rack and pinion kit specifically designed for the '71-73 Mustang. However, due to the versatility in how our rack mounts to the vehicle, it can be easily adapted to fit your car. (If you were considering installing an IRS, this is completely within reason.) The process is similar to this
Fairlane installation. Unfortunately, I don't have an official set of instructions for the '71-73, but the install can be done without too much grief.
Subframe Connectors
Our subframe connector system does not fit the '71-73, but there are other manufacturers that do offer them.
Rear Leaf-Spring Suspension
You're a bit limited on the rear
suspension choices as well. We do have a rather nice leaf-spring package that includes our adjustable valve VariShocks; the perfect compliment to the front
suspension. If you wanted to take the next performance step, a
torque arm can be added that includes mounting tabs for your existing rear end housing. Or, a FAB9 housing can be factory assembly with the mounting tabs. You will have to fabricate a simple crossmember to anchor the front end of the torque arm.
This obviously is not a leaf-spring housing, but you can see the simple mounting method. We also, offer a weld fixture to correctly position the tabs.
Canted 4-Link
If you really want to do something cool that works extremely well, we offer a weld-in triangulated 4-link system through our Chassisworks product line.
Another StangNet member posted some
pictures from his project. He selected our billet-aluminum links, but we also offer adjustable-length tubular steel links, which I would recommend for a handling focused project.
Sorry, didn't have a smaller image on the web server.
NOTE: There are different types of 4-link systems. Chassisworks manufactures at least half-a-dozen different styles of 4-links. Some of which are designed specifically for drag racing and others are setup with geometry that is more suited for street or handling applications, such as the canted-4-link shown above.