if I remember from dave haynie's archives of zorro III docs, zorro III is set up for 2 gigs per slot. 4 gigs max with the lower parts used by system. what would anyone need anything over 128 megs for though, other than 3d rendering?
btw someone already mentioned getting a 4000, I'd say skip it, most video cards and accelerators work in either and 4000's are expensive. unless you have aga software and no access to an aga machine. you can build a souped up 3k for the same as a base 4k.