I tried a lots of things on the RB5 platform since the first Vega RB5.
Always found SB better until I tried those Losi front springs. These are quite hard and may be fine tuned but allow to keep fast direction changes and good steering.
I used RB5 long tops and short ballcups and checked I was about the same as SB. I also use 25mm screws on top to clear the tower (but bent some on hard floors).
More droop on the rear is better Roger ?
That might not be the best setup but it's mine and the car is totally dialed for my driving and that's something