Be sure to research the pro's and cons of a rack and pinion steering system. Marketing people at the companies that sell them and the car mags that are paid to advertise them are all about pushing the pluses while glossing over the negatives that can kill you if you get it wrong.
GM didn't use a rack and pinion for ever because thaey had invented the recirculating ball Saginaw power steering used by GM Ford and Chrysler (which at the time was called Jeep).
I used to use either a Corvair or a Vega Saginaw gear box on my race cars when I wanted a faster acting steering; as they were small and light and didn't suffer from bump steer Ackerman angles or any of the other things that crop up in a rack and pinion system if everything in your front suspension isn't aligned to the movement of the rack.
I currently have power assist variable ratio rack and pinion steering with 10" x 20" inch wheels on my pick-up, but it came that way from the factory so I didn't have to engineer or fabricate anything.