yea it should not be hard to add the termination, but resistors alone do nothing for noise, you need a rc network

by the time you figure out what noise is present and do the math it might be easier just to buy a terminator

and if anyone read my google fu post IT DOES NOT NEED TO BE BLACK! they made these things in 3 revisions, the black one, the A model which is beige / plat, and a C revision which is kind of a generic catch all after the fact and the II models started hitting the second hand market and needed more dongles

dont get me wrong I understand why you want the black one, but if I were itching to get my IIfx up and running (and I would) I would just snag the first one I could get my hands on then worry about authenticity at my leisure