I lowered mine 2" on a '76 which has a different type of mounting. Your's looks easier to do as far as that is concerned.
 I had to lenghten my steering shaft. I went with a u-joint style joint on both ends.
 And there is the 'issue of bump steer' I found out to late that they make kits to overcome that.
 You may want to contact 71pintoracer. I believe he has done that on his car. He has a lot of knowledge
with an early V-8 conversion.

For lowered racks, bumpsteer correction spacers: http://www.speedwaymotors.com/Bump-Steer-Spacer-for-Pinto-Spindle,35534.html
 
or the entire "kit": http://www.speedwaymotors.com/Pinto-Spindle-Bump-Steer-Correction-Kits,52425.html
 
Mike

Reeves.

The bump steer kits go on the bottoms of the spindles and take the place of the outer tie rod end or relocate it depending on the kit.   While there is lots of info on correctly designing the whole deal using shorter inners to change the initial pivot points on the rack to match the line between the upper and lower arm pivots the important detail is you want to lower the tie rod end at the spindle in proportion to the rack .   ideally the tie rod angle should be parallel with the suspension arms through the entire up and down travel.  this should be sufficient to make it drivable without wanting to rip the wheel out of your hands

those spacers just lower the outers an arbitrary amount.  to do it right get some of these
http://www.speedwaymotors.com/Adjustable-Tie-Rod-Adapter-Stud-to-Heim,3333.html
these
http://www.speedwaymotors.com/Precision-Male-RH-Heims,80.html
etc and then you can set it at the proper location


OhSix'

The second link is for a male type heim. I contacted them to see if they have the right ends for my car.

Disclaimer: not having done this, not sure what method would be easiest/best/safest.  Also I do not know correct bump steer fixes.  However it is easy to speculate like this.
 
The steering arm tapered hole on the 73 spindle is the larger size and should bolt in.  An alternative would be to use a tapered reamer to enlarge the 72 hole.  I do not know the angle needed, as they sell a couple different angle reamers.  A local machine shop may be able to do it also.
 
As for the heim size mismatch, maybe make an adapter tube.  Thread one end of a tube for the 1/2" tie rod and the other end for the 5/8" heim.  Wrote to Flamming River who sells 71-72 racks and they said most people use a straight bolt to attach a heim to the spindle steering arm on race cars.  Based on my measurements, the 72 spindle tapered hole could be drilled out to a straight 1/2" hole.
 
Since you are relocating the rack and have to make new mounts, maybe use a 74-80 rack.  The member "fordmastertech" did this to a 73 Pinto, see link.  The 72 spindle tapered hole would need enlargement for this.  The linked photos no longer work but I saved most of them in Word (file too large to post here).  If you want a copy, pm me your email address and I will send them to you.
http://www.fordpinto.com/general-pinto-talk/build-pics-1973-turbo-coupe/msg102503/#msg102503