SpeedGeek is correct.
Is this going into a 16 bit memory controller in an A2000, A500 or are they going into an A4000 or another accelerator board?
Example A4000 can benefit from 60ns memory, (you must use a ramsey G set program to get the full speed, can be found on Aminet)
An 68000 with a 16 bus probably cannot take advantage of anything under 100ns.