K-Member / Rack & Pinion Steering Suggestions

One good thing, in regard to headers, with a torsion bar-less car is that you can run a nice big 1-7/8” header primary without trouble.

And that goes along with need and application. Why would you need such a big primary? 550-600 hp. If you have that then you may be counting pounds, you may be looking at needing quicker spring rate changes (coil-overs win over t-bars for ease and speed of changes), you will already be stiffening the sub-frame and tying the front frame rails to the firewall.
If you aren’t doing ALL these things I would advise you stay with a torsion bar system.
If you want a serious handling t-bar setup I highly suggest you hot tank and seam weld your k-frame. Chrysler was criminal in the shoddiness of their k-frame welds.