DOT 5 fluid has 2 areas where it is different than DOT 3 or 4. DOT 5 doesn't absorb moisture and it won't strip paint if spilled on a finished surface. When heated from excessive brake use it does make the pedal lose some of its feel.
The hot rod and custom magazines all seem to make a big deal about using DOT 5 fluid and invariably they mention about how it won't hurt the paint if you dribble some during brake service. All the car builders I know use DOT 3 or 4 and are simply careful about filling or bleeding to the system so it doesn't get on painted finishes.
Your new system won't suffer any if you use the DOT 3 or 4 fluid. The only harm will come if you spill it all over your new paint.
Fill it, bleed it, drive it.
Mike
