It was my experience in rebuilding the cylinders on my LW-6 that it's best to disassemble one and measure the cup seals as there are many different kits available for the same size cylinders. A big plus is that the replacement cup seals are polyurethane and not rubber or neoprene (at least mine were). I know Tommy or Ronald and Phillip stock the kits but individual pieces may be available at your local hydraulic repair shop or NAPA. Other dealers may stock kits as well.
I talked to Tommy and he doesn't have the kits for the LW-7. I'll check with Ron & Phillip, if they don't have the kits then I'll pull the cylinders apart and then match up the seals at a seal shop.