Lowering the maverick . . .

dam those are sexy!

 

From an engineering perspective, this kit provides several advantages over the Total Control kit.

http://autofabcart.net/1967-1970mustangtubularcontrolarmsandcoil-overconversionkit.aspx

The Total Control kit uses the same spring mount location as the stock spring. The Autofab kit mounts the lower end of the coilover just inboard of the spindle on the lower control arm. This give the advantage of better leverage which means lighter front springs and a better motion ratio. The lighter front springs will give you a quicker response to bumps and better ability for the tire to stay in contact with the pavement.

 

this is a similar one:
http://www.totalcontrolproducts.com/fcoc-fd.html

 

Mine is 24 1/2" in the front and 26" rear.

 

I see your point about leverage since the mount on the LCA is further away from the point of rotation of the LCA but since the spindle is solid and attaches the LCA to the UCA I don't see the leverage making any difference.
The shock travel isn't changing much either it appears since the upper part of the shock is now a new solid piece that sits much lower than the shock tower. That's how I understand it.

 

It is a matter of leverage. The spring acts on the control arm closer to the wheel, therefore it requires less effort to move the control arm than if the spring was mounted half way down the arm. This allows you to run lighter springs which will respond faster, have less weight and give a smoother, more compliant ride.