440ZX, technically, can use up to 128 Mbits per SDRAM chip, 128 MBytes per DIMM side, 256 MBytes per DIMM. However, not all BIOSes for these boards know about these.
In other words, use a proper DIMM (you need the "16x8" flavor, 16 chips, each 16Mbits large and 8 bits wide) and try it out. You won't damage anything if your BIOS doesn't handle them.
regards, Peter