Cray-1 from that era had 80 Mhz clock and 8 Megabytes (1 Megaword) memory. But had peak floating point of 160 mega flops. Also, no cache. But highly interleaved main memory.
The Cray designs and the IBM mainframes were built for different requirements. The Cray machines were designed for the highest possible processor speed while mainframes were much more geared towards business needs, where you do a lot of IO and just a little bit of processing on the data, before sending it back to tape.