What Bob was trying to say was (I think), shortening the control arms for the sake of your wheel offset is not a good idea. You're taking a big gamble with the cars handling by offhandedly making this change. Modifying control arms, and tie rods is for suspension gurus, not us unwashed masses. Leave the suspension geometry alone, and modify the wheel offset to where you need it.
Go to the heidts.com web site and read their tech article (it is also in their catalog) about Mustang II front suspensions, "bump steer", and what not to modify unless you know what you're doing.
Can't say I'm any great fan of Fords engineering prowess, but primitive as it is, the MII front suspension does work.
That being said, there are some things that can, and some things that must be modified with the MII on a Cobra (or any other car it is adapted to).
Can modify. You can replace the strut rod with a strutrodless lower control arm. There are some good, and beefy conversion kits out there, and there are some that look like they will twist like spaghetti the first time you hit the brakes. Starting with a bare frame, it can be done easily as there is some welding to do. Retrofitting after the body is on is more difficult. The strut rod does make for a beefy, and well supported front suspension. The problem is not the strut rod itself, but the soft rubber OEM style strut rod bushing that allows the wheel to move up & down (which it's supposed to do), and also front and rearward (which it's not supposed to do, not on a Cobra anyway). Solution, use urethane strut rod bushings.
Must modify. The inside mounting of the upper control arm, clamps the the arm to the frame with bolts. Ford seems to think that the serrations on the underside of the arm will hold it firmly to the frame when aligned. Provided, of course, that you can get an alignment shop to do it for you. ($69 for several hours worth of work is not particularly profitable for the shop) The first bump I went over collapsed the arms to the inner edge of the slots.
Solution. Tom Beroth of
www.bethania-garage.com makes a MII upper control arm bracket that lets the alignment shop set the alignment with shims (just like real cars - sentements to Ford engineering again, and re-engineering that SHOULD have been done by the kit maker). The alignment, once (and easily) set, stays put.