Ridetech Rear shock question

[toofun]

Got a question on setting up the rear coil overs on a 68 camaro. I tried searching for the answer but couldnt find it so here it goes.. Installed an airbar into the car, set the ride height at 14.5 inches from eyelet to eyelet per the instructions. I had to swap out the springs I had cause PTS (months ago) sent me 500lb springs instead of the 200 ridetech said my camaro took. (BTW thanks ridetech for the very speedy swap and also for the longer bars you made up for me to deal with my moser rear issue that worked out great!!) Ok so the shocks measure approx 16 1/2 inches extended from eyelet to eyelet. So I assemble the shocks with the spring set at 0 preload and install it into the rear, but when I put the car on the ground it still only compresses 1/2 inch for a total eyelet to eyelet measurement of 16 inches. I dont see any binding issues anywhere and I can bounce on the car with the suspension moving. I know that it is suppose to sit at 14.5 inches eyelet to eyelet with the car on the ground(ride height) but it is 1 1/2 inches off from that. I pulled some engraved numbers off of the shocks but dont know what they mean they were 11166, 982-10-805, and 362674. Again I dont know if that corrulates to anything. I cant lower the spin nut anymore for fear of it coming out of the pocket. Has anyone else ran into this situation? Am I doing something wrong? Thanks in advance!