Three simple things to remember when using the A3640 in an A3000 (other than making the jumper settings on the m/b):
1) With Kickstart 3.1 roms, you can use either static column or page mode zips or a zip-to-simm adapter. The problem with static column vs. page mode zips only surfaces with 2.04 roms.
2) Rev3.0 A3640s won't work in any A3000. You need at least a version 3.1 or 3.2 A3640. Either will work with Rev2DMAC and Rev4 Ramsey combo (no need to source Rev4DMAC and Rev7Ramsey).
3) Because of the low drive bridge, you need to source a low-profile heat sink for the A3640, especially if you plan to overclock it.