For the shock contact MX Tech
. The shock is a Kayaba/KYB 43MM (I think) and if you want to update a lot of later KYB stuff retrofits. If you just want a service,i.e. fresh oil and a charge any good off road shop should have a suspension guy on staff.
On the forks. I have an '80 YZ465 w/'82 forks. I did the Cartridge Emulators and what a difference. The install is doable by anyone w/ a sense of how to drill a hole and deburr it. Well worth the effort for racing.
If you haven't yet upgrade the springs for your weight for starters.