I read about a guy who has a 350Mhz BPPC.
He took the CPU from a Mac card and got some local electronics company to put it on his blizzard and do the overclock. Thats the fastest Amiga I've heard about so far. Some 300Mhz CSPPC's too.
I think the stock 603e/604e CPU's on Phase5 cards max out at about 266Mhz so going higher than that will mean getting a old mac CPU card (which are really cheap - like $20 on ebay) and taking the CPU from it, but you need a lot of experience to do this (or a knowledgeable local electronics company)
