rack and pinion
 

Has anyone installed a rac and pinion steering in their early Mustang? And if so how well does it perform.

I haven't but try www.totalcontrolproducts.com
for a slick looking made-to-fit rack and pinion for early Mustangs. Just bring a big checkbook! I've looked at early rack/pinions
in LTD II's and I'll bet they could be adapted with maybe making a mounting bracket that would attach to the frame both sides and mount
the rack about where the current drag link and steering cylinder mount. The LTD II's also have what should work for steering column joints to hook to the rack.

Let me know if you come up with anything!!