Do NOT just get a Fox rack and toss it in. Unless you have experience designing suspension systems and setting bumpsteer, Ackermann, and packaging everything, you'll likely have a car that is worse than before. Your best bet is to get a ready-made kit. Total Control Products has the backing of Chris Alston's ChassisWorks, and they have lots of experience with suspension systems. A rack and pinion system has fewer points of movement than the factory recirculating ball system, and so it will wear less and maintain better steering feel throughout the life of the car. Not to mention, I feel that a rack and pinion system packages better than the recirculating ball system, especially with power steering.
Proud owner of a '65 289 coupe w/ C4 (for now). Equipped with Edelbrock Performer intake, 600 cfm carb, Comp Cams Xtreme Energy valvetrain with XE262H cam, MSD ignition, and ported heads. Suspended by 600# 1" drop front and stock rear springs, KYB shocks front, 1" front sway bar, 1" Shelby drop, Griggs Racing GR350 rear suspension. Many more mods to come!