I have something similar - using a compaq uwscsi 9gb drive.
I found a small 68 ribbon cable (actually used internally in rack mount servers - working in an it company has its benefits! ;o) ) which had 2 connections, plus a permenant inline terminator at one end.
I have a 50 pin ribbon cable from the cyberscsi, to a 50 pin male to 68 pin female micro connector, which I then have the lead plugged into.
I believe the problem with adapters such as this is that you need to make sure you are using a terminator that terminates all 68 pins on the UW side. Using a 50 pin terminator means you still have 18 pins unterminated.
If you need more info, piccies etc let me know.
