150# rear coilover spring rate to light?

[skeeterbug]

I am trying to finish up my winter upgrades before local test and tune starts Feb. 3rd. Ended the season with my best ever of 7.70 @ 87mph with 1.70
60', much improved from consistent 7.82 @ 85mph w/ 1.83 60'. Not to bad of an improvement I guess just for raising the trailing arm mounts up and jeep coil spring swap from stiff lowering coil springs. Started seasons end Nov. 2012 with much needed 1-1/2 to 1-3/4 primary header 3" collector swap, dynomax 6" L race bulletts dumping on the pavement. Trying to pickup the short time with a 3.73 to 5.13 Richmond swap, offset some by 28x11.5 to 31x18.5 change. Lost 80 lbs. of interior weight by ditching the explorer buckets and square tubing mounts for one kirkey pro-street cl find. I then decided utilize my other cl score of m/t et fronts, WHEEL TIME, sold my set of 20/22 coy c-5 street wheels to finance the new shiny stuff. This is where the trouble started, ordered 15x5 front and 15x14 revolvers from holeshot wheel (love em, worth every penny) skinned the rears with hoosier 31x18.5x15's. Back spacing is spot on...but the drivers rear contacts the lip of the wheelwell under mild acceleration promting the need for coilovers to fine tune the rear suspension and ride height. I will be ordering strange coilovers very soon just wondering if you all think 150# spring rate will be to light for my lwb fleetside w/ no bed floor at all. Floor will be all aluminum as soon as suspension is finished up. Sorry for the long story but the season is coming and I never wound down.
What spring rate are most of you fellow haulers running?