I have the same set up, my springs are the HD (CS036R?) OME "dakar", my jeep is a RDH '84 cj7, soft top, 4.2 6cyl,Rocky Road yj conversion kit (hagers and shackles),soft top.
rear right side is lower than the left side of approx 3/4 of an inch. Note that driver and D300 transfer case are on the same side on my cj (RHD), also the tyre carrier is mounted on the right side, this in my opinion will contribute to my rear right spring to sag.
An OME expert at ARB suggested me to try their leveling kit, basically 2 spacers to install under the front and rear left spring (from memory), basically it did not solved the problem, he said that it's a frame related problem most of the time, frame can be a bit offset or twisted...In my opinion it's a springs related problem, they should be match in pairs...
I installed a pair of OME extra leafs at the front (coz was way lower) and I'll probably do the same at the rear if it get worst, plus I'll try to swap left to right..
The "+" or "-" symbols identify a spring that has a sligthly higher or lower load rate/under load height or something like that, that's what I been told by the seller who pointed me to "+" springs on all 4 corners, the + or - could help to match a set of springs... "0" should be neutral or std rate for that spring model,
I suggest you to break-in the springs for a while, take 'em off and measure the arc height of the springs, write it on the springs, then move the higher (should be also a "+") on the driver side.
with a winch installed I'll consider to run an extra leaf to level with the rear, I think it's a matter of swapping them around...an a bit of luck..
hope to help,