Lance,
The Boss '9 type shock towers do not make the car sit lower. the difference is that they are cut down and somewhat more outboard than the Boss 302/standard Mustang units to make room for the "Blue Crescent" Boss 429 engine. Understand FITTER is somewhat anal retentive about the details....put a piece of coal up his butt and get a diamond back
BTW, Fred Cady does the decal sheet with the correct black stripes and other detail decals but sadly they are not reflective like the real thing
I have a couple of the old Jeff Hitchen die cast "shaker" hood scoops that were made to allow conversion of the Boss 429 kit into the Boss 302 back in the early 80's when Monogram released it.
There are some other issues with the body shapes but not much you can do about them. One big improvement is to remove the cast in "B" pillar from the kit body. This is actually a narrow piece of stainless trim that is attached to the pivoting quarter window and not nearly as thick or wide as the kit replicates. Best modeled with piece of thin plastruct and some foil...
Build a Boss and post the pictures here! And remember what Parnelli Jones, the revered Boss Trans-Am racer said..."if you're still in control, you're not going fast enough!" worn by legions of Boss faithful on T-Shirts!
Rick