Rebuilding an old Rockshox SID XC

[N3BW]

As stated in the title, I have an old (approx 20 years old) Rockshox SID XC in a shed-find frame that I'd like to bring back to life. The shock seems to be in ok condition with the exception of the large quantity of oil left on the shaft after compressing slightly. As far as I can tell no one sells a rebuild kit for that model/year any more. Is it feasible to piece together my own rebuild kit by measuring each o-ring? Also, are there any other wear parts which should be replaced when servicing this shock?

Thanks,

Ben