Lucky,
I have stock steering with no power on both my cars. So the first question is do you want power assisted steering. In my opinion the 3 turn lock to lock of stock power assisted steering is much more sporty than the 5 or 4 turn lock to lock of standard non-power steering. someday I may convert to power, but do no like the horse power loss or hoses, rams, control valves. But a finely tuned stock power steering is a nice feel in my opinion.
Next is exhaust thoughts. Long tube headers play havoc with power steering hose routing. The long tube headers land right in the middle of the control valve. This leads to routing headaches. I have even started a small fire in my header area due to a broken and misting spray from the high pressure hose. That was it for me!!
Also most headers require you to drop the end of the ram to get under the collector. Low clearance problems and added stress to the torque box due to increased leverage by the ram against it.
The next part in cost and the thought of a power assisted Rack and Pinion set up. The Fatman kit is awesome if you absolutely want a rack. Early conversions suffered from increased turning radius and a "darty" slash over sensitive feel. They newer versions are much better.
Soooo.... Why do I tell you all this stuff-o-la??
1. Stock exhaust = Stock power system. Stock exhaust means a mild engine build.
2. Total Control is cheaper when you add in all the parts. It uses the firewall as Ford intended. It will work with standard non-power or standard power steering. The standard power steering leaves you with stock exhaust manifolds, shorty headers, or Hipo manifolds. The shorty and even the Hipo manifolds require some creative hose routing is some cases. Now the Borgeson conversion removes the control valve and ram, and removes the troublesome lower hose routing that moves back and forth with the steering. It will fit right into the TC conversion.
Basically TC and stock standard or Borgeson power steering conversion will improve your handling over stock and allow the use of any long tube header.
3. Fatman. Most expensive and must go to a rack. Either a power or standard rack. Allows for any long tube header. In my opinion if you had to equal cars on a road track, the rack verses the standard steering would be very hard to discern in actual time improvement.
The first consideration is exhaust for you. If you are going for big power then you need long tube headers and all that goes with that. Here is a link to the best fitting small block headers on the market in my opinion. I have them on both my cars. They tuck up so tight they are just as high as small diameter stock exhaust. I have the #2 for stock exhaust port location configuration. They work great with most high performance heads on the market.
http://www.fordpowertrain.com/FPAindex/Mustang1.htm
Here is a picture under my car. Notice the relationship ship to the torque box frame. By the way, that is 3 inch exhaust!