Steve,

Not sure why you think you want a rack and pinion set up on a straight axle. This is a generally unsatisfactory set up.
If you look at most conventional rack setups the rack is mounted securely to the front crossmember and the tie rods run out to the spindles parallel to the lower control arms (independent front end). The tie rods must run parallel to the control arms and have similarly located pivot points for the sake of proper steering geometry, otherwise you'll get some shakey handling. Its called "bump steer", that is, whenever you hit a bump the mismatch in the geometry makes an unintended movement at the spindle, causing the car to "dart" from side to side.
So what are your options for a straight axle set up?
If you mount the rack solidly to the frame then the tie rods will be at severe angles to reach down to the spindles. Very bad!
The way most people who have tried this is to mount the rack to the axle. That makes it easy to maintain parallelism to the axle and avoids bump steer at that area. Personally I think it makes the axle look clunky, but more importantly, you then have to deal with a way to connect the rack to the steering column that will allow movement when the axle travels up and down. A slip joint along with universal joints in the shaft connecting the two could allow this, but again, that movement usually contributes to mismatched geometry and resultant bump steer.
Of course the straight axle, gasser set up, wasn't really about handling anyway. It was just a way to aim the car for a short, hopefully straight, shot down the strip.