helps to know what year bike... are these oem or aftermarket... and is the problem just leaking... replacing the seals is a lot cheaper than the rebuild kit you mention.... there is a 1200 rebuild thread I did on the "howto" forum
1980 GL1100 Standard. With OEM shocks that hold air but bottom out when it sees a bump.
I just rebuilt mine or should I say took them apart and put ATF fluid in them? one shock was froze, so I took them both apart, it is a messy job but not hard if you have an air compressor. Take them off pull the boots remove snap ring and try and drain them as much as possible wrap a few old rags around them and put one end in a vise and hang on to the other end with old rags because you are about to get a bath in ATF, apply air in spurts and it will come apart and the ATF will go every where, clean them inspect the seals and replace if they leaked put the correct amount of ATF and put them back together it is fun trying to get them back together because you have to put all the parts in at the same time and it don't look like there is enough room because the fluid is near the top but it will go together believe me..good luck and if you need any help give a yell..till then 8)