1981 GPz550 forks--what oil, and how much?

I'm putting together a set of 1981 GPz550 forks which I took apart in --gulp--1989. Progressive springs from that same era.

What weight fork oil seems to work the best on these older Kawi forks, and also, how much of it?

Forks are drained but not taken completely apart.

Thanks in advance.

Hey there. Good luck with that
I kinda' did something similar with KZombie. Dismantled almost 10 years ago and now "finishing" what I started. :laugh:

Anyway to your question. A chart in my 550 manual explains it as based upon several factors including model designation. Assuming I got this right. A GPz is the model designation of D1 ...
Here's the dope on the chart for a D1:
Air - range is 8.5-11.5 psi. Setting is 10psi
Oil - SAE 5w20
Dry capacity is 8.3oz / 245cc.
Wet capacity is 7.6oz / 225cc
Oil level 20-1/2" / 520mm
Oil level is checked with fork fully extended and spring removed.

Hope that helps! There hasn't been much I've done on these bikes that nearly defeated me but dismantling/rebuilding the forks was certainly one of the more challenging things!