Hey Opus...
18 meg max. IDE is WAY faster in the ultras, and you can back from IDE to SCSI (say if you had a zip or jaz on your scsi bus in you computer but an internal IDE drive in your sampler you could go from the HD in the sampler to a backup device on the SCSI bus as long as its emu format)
as for the RAM..you can add flash RAM that is non-volatile so you can store sounds there, and yeah, you can use 64 meg chips but I dont know if your sampler will see the stuff you have (roller says he doesnt think Emus see double sided RAM)
how about...try it?