[Jim Bremner]

Matt,

What I would do is add bracing from the shock towers. If you want to add plenty of stiffness there's a 23 piece kit from Dr. Gas. They include shock towers from the inside and the outside, There's other plates that stiffen the footwell area and the sub-frame. These Mustangs are made up of folded sheet metal. I would say that most of the sheet metal is in the 16 gauge or thinner.

Don't worry about high rate of spring rate. GT springs are plenty soft around 500#'s I ran 900 pound springs on the front. Rear springs are 160# and I had 250# springs. It rode like a honda civic.

Other area of flex is the rear shackles for the leaf springs I had 1/4 plate aluminum shackles that had 1/2" bolts vs. the tiny stamped steel ones with 7/16" bolts.

Front A-arms can get the "Shelby drop" it changes the arc of the a-arms as the wheel rises. There's a strut that locates the lower a-arm Don't get fancy with aftermarket bushings, There's a bind in the system and you will crack the mounts if your bushing is too stiff.

A really cool race shop on the east coast is Cobra Automotive. YES, you want to keep the car as stock as you can, they can help you make it safer to drive.

Good news is that the bugs of the early cars are worked out by 1970! That and they no longer had a solid non collapsing steering shaft like '67 and older.