Yes BPPC can be upgraded to 060 but must be done by someone who knows what they are doing! contact member stachu100 he has done a couple for me in the past and his work is top notch. Also the PPC side can be upgraded to 300/330mhz with new chip. It's well worth the upgrade if you have a 160, not so much if you have a 240 already.
For 060 if you get the Rev6 CPU you can run safely at 66mhz which is a really nice boost for your Amiga