I like the idea of visiting JS Air cushion stocks as a plan as well.
They should have a "Try Gun" set up ...so they can evaluate what you're saying .../work with you a little on the "Try Gun" and then evaluate how to set your gun up so its the same.
...../ but I really wish you'd tape a Jones pad or something on your current gun ...and snap a few photos.../ ....it would at least be good for a laugh.
Now for a serious answer: If you were to put a Jones pad, or something like it on a GraCoil or a standard stock ...you set it up at home - about where you think you want it - where it seems comfortable - and you have the midrib bead and the front bead stacked in a figure 8 ...when you mount the gun...
...to evalute the setup / how to adjust it at home .. ( use the old drill - look at a light switch on the wall accross a room at home (unloaded gun of course) ...close your eyes / don't move your head - mount the shotgun so it feels comfortable - and open your eyes and see if you are still looking at the switch.
.... then take it to the pattern board ( with a full choke in - at about 25 yds ...and dial in the point of Impact) with small adjustments in the comb or the jones pad or both.
( and while you're at JS Air Cushion - have them cut the adj comb in the gun and install the hardware) !! Yes, I told you you'd regret not buying it that way out of the factory ...but it'd be rude of me to say, I told you so ...)