Rack and pinion
Midlength headers is the fix
$10 says the header collector would go right through where the steering shaft would go if you mounted a rack behind the k-frame. Pretty sure a rack there would require custom headers. Maybe not, never tried it, just my bet.
I'm all for doing things just because you want to. Heck, I sectioned a later k-frame to fit in an early A-Body just because I wanted spool mounts, a better idler mount and the later sway bar. Was it going to make enough difference to be worth the effort I put into it? Probably not. But I wanted to do it.
I could use some of the same logic with the G3 swap I am working towards, but at least that one has been done multiple times and been shown to work well.
But I doubt the effort to get a rear-steer rack mounted and working is worth the effort based on past attempts. But if you want to do it, more power to you. Get it done and let us know how it went and if the custom headers, oil pan, etc. are worth it.
BTW, I still have the modified k-frame even though the car is long gone. I keep it around to remind me what a fools errand it was.
