Okay here are the chips you need :
Replace Denise w/ super denise
Replace Agnus w/ Fat/Fatter Agnus
You don't need a "gary" or "buster" as there is no Zorro 2 bus on 500s. Paula was never upgraded so no need to replace.
On Ebay they have the chips needed.
could you tell me if could replace my dead angus 8371 / 4488 / 22 with a
Commodore Amiga 8372A 8372 / 8370 Agnus Chip