I'd stay away from the Heidt's front subframe. It's probably a quality piece, but you're stuck with their control arms and their steering, and therefore their geometry, which is probably designed for "Pro Touring." If you want to upgrade the front subframe, I'd consider the ones from Detroit Speed and Engineering and Speed Tech Performance. Both are compatible with stock and aftermarket control arms. The DSE Unit comes with a front-steer rack, so I don't know if you can use your stock spindles... maybe you can just swap the steering arms side to side? The Speed Tech subframe comes with a Unisteer rear-steer rack, so that one should have no problems with stock spindles.
http://www.detroitspeed.com/productpages/subframe.htm
http://www.speedtech-performance.com...rod/prd157.htm