I agree -- don't go with a reverse design unless you absolutely have to for clearance reasons, then know how it's going to affect driving qualities. The reversed arms can lift the rear end when braking hard as well as "unplant" the tires as Air Ride put it. So it can increase front end dive (by lifting the rear). There should be plenty room under your car. If it's mostly a show car (trailer/garage queen) then you can probably live with it easy enough.
In all my years of race car driving I have to disagree with the braking forces causing the axle to lift. If the nose drops under decelleration the rear could lift with soft shocks and short bar lenght to induce enough bar angle. But with 20" bars, I've never seen it happen.
Brakes alone forces don't affect the rear axle rotion unless the rotor is attached to the chassis on a lever system. Racers call that floated brakes. Engine braking alone, will affect the rear axle though. If the bars are kept at 20" the affect's are diminished to almost non. Brakes should be setup so the front will lock just before the rear because it's the easiest thing to feel through the wheel and correct for.
You might here a term called "trail braking" in racing sometimes. That's means applying the brake to eliminate the engine braking affect's for better turn in. Very easy to do, very hard to master, Amazing when it's done right.
