Farmer,
Look at the Roberts Reventon Build Thread #25 and there is a detailed description of why those 4" travel shocks are going to be very difficult or even impossible to use on a Chassisworks chassis. I think it is going to be the same reasons for a Naerc chassis. But what travel length do the plans call for? And what tire and wheel size, car weight, and spring rate (all of which must first be determined to select and properly locate the correct shock) did they use? Are you using the same?
Edit: There is more info at Kitcentral, Coil Shock Adjustment Thread, Feb. 20.
