afaik you cant use a2000 agnus in 3000
The agnus are basically all compatible. The main difference is the pin configuration, but that can be fixed using an adapter.
If you want one that will drop in then get one that is marked exactly the same (the year and week can be different but nothing else).
The 8372/8372A/8372B doesn't specify the pin configuration, there is another number that is used for that.