Rowan, I just now found them. We had major home remodeling done last summer and everything got shifted about incuding our computer work areas, complicating the search. However, I finally remembered to look in an old spot where i used to put all system disks and there they were! What a relief!
It is a two disk set--the OS9 installer is bundled with the Applications installer on Disk 1. The disks have somewhat different part numbers; Disk 1 has 691-4873-A and Disk 2 has 2Z691-4873. You should try to get both because I can't tell from the directory if the Disk 1 OS9 installer needs to pull files from Disk 2.
You might want to try what I am doing. That is to search around for used computers of the same model.
I'm right there with you, my friend. My son had an identical G4 MDD to mine and, when he upgraded to an Intel iMac and had no extra room in his small apartment, he asked what he should do with the lightly-used G4. My response was a very emphatic. "Send it home!" So it's downstairs awaiting any call for service. It also has a new power supply, a known weak point in G4 MDDs originally fitted with the so-called "quieter and improved" 360W power supplies. The original 400W supplies sounded like Training Day at the bomber base but, in the long run, were more reliable.
If a scan of the disk faces would help, let me know.