Thank you for the help and advice everyone!
Tenacious: I got this 3000 second-hand back in the summer of '91 (upgrading from a 500), and it came with 1 MB of Chip and 4MB of Fast (perhaps 3, but I think it is 4). It has a factory sticker on the back listing the specs (25MHz, 100MB HDD, RAM specs), so I'm pretty sure it was a default configuration. Other than upgrading to 3.1 in '98 I've kept her stock, but that's about to change.

joekster: Thanks for the info! I found a Japanese site that listed the RAM as being 120ns (
Japanese Amiga Site) , but if it is indeed 100 I will buy that. As for the ISA graphics cards, are there any particular brands or models to look for? Or are they all pretty much populated with the right kind of chips?
konishipol: That's also very good to know, I'll check on 500 RAM expansions as well. I knew that the zips were hard to come by, so I'm relieved to know it's not the same case for the dips!