For anyone that is interested, I e-mailed to enquire about the speed of their 32meg simms being 70ns and the effects this would have on the performance of the card and got the following reply.
"Yes we use all the same make and speed, we run them all at 60ns through a tester so regardless if it is marked 70 or 60ms it works fine (we try to use 60ns if available ofcourse). Most brand name ram can run much faster than marked, we run motorola ram through our tester at 40ns when it was marked 80ns"