Yup 110 rears are 7" in diameter not 6" so will not fit. OE 110 fronts are either progressive 155-215 lbs/inch or are 225 lbs/inch the former are the same as standard Disco 1 rears and will be yellow/yellow or white/white
Heavy duty OE 90 rears will fit and are progressive 210-240 they are green/yellow/red
Heavy duty Disco 1 units are Pink/Yellow/Red and are progressive at 200 to 330
I swapped from the Disco Heavy duty units to 764's (240lbs/inch and plus 40mm. I used Gwyn Lewis spacers on the HD units to make up the clearance for 245/75's on zero offset modular's. The spacers are 6mm circular plates. The OE HD spring gives about plus 25mm so I upped that with 4 spacers. Howvere the HD springs are simply too hard when loaded. I destroyed the bushes on the GAZ cellular shocks (not very good) in 500 miles and then lunched the shocks in 2k....
I swapped over to the 764's with 12mm of spacers and they are excellent. The biggest drawback is that due to the thinner, better quality wire in the coil, there is more upward movement in the spring before it becomes coil bound (the HD units become coil bound before they hit the bump stop) so I was hitting the wheel arch. A quick Camel cut sorted that.
At the time I was unaware the new Devo-Tech springs from Devon 4x4 are made by Eibach. they are £50 cheaper than the 764's - additionally since OME no longer get their products made in Australia, but in China, the coating quality has gone down hill. King Springs used to make OME springs; and Monroe made the shocks (with SuperPro bushes) - all very good quality control. Eibach are made in Europe. The coating is far better quality and lasts longer. I am waiting to see if the steel on the OME springs is still as good