Couple of things:

1) The ROAR minimum weight for 1/12 scale is 28 oz. You are experiencing some shifts in that to equalize things when people use the personal transponders for timing & scoring. That is where the 29 oz limit has come in. The 29 oz minimum weight includes the transponder and gets you close to 28 oz car weight. Rechargable transponders that are supplied by the tracks are just shy of 1 oz. and the personal transponders are about .6 oz. The 29 oz is a number picked to eliminate an advantage for people using the personal transponder. Sort of like handicaping horse racing.

2) The three shock setup for the rear of the cars is very popular on oval. It is very rarely used in on-road. Delta had a car about 13 years ago, the Spider, that had a 3 shock rear suspension. But in reality, the current setups of dampening discs, or dampening tubes with springs or t-bars is the most applicable to on-road racing. They are lighter than the 3 shock system, and can be setup with lower spring constants and softer dampening than the shock. Some tracks require that.

I hope that helps. Keep the questions and recommendations coming.