Silly perhaps, but has anyone tried this?

[olegil]

One thing to remember is that the 68060 doesn't use a double clock for anything. A 25MHz 68040 is run from a 50MHz clock in 100% of the cases I've seen. A 50MHz 68060 is run from a 50MHz clock. There's one pin for bclk and one for pclk (unless my memory is wrong, I have looked at a 68k cpu for 2 years now), on the 040 these are different but 060 the same. I think :-)

Except for this there's a couple of odd differences I don't remember at the moment. Anyway, it is doable, because Motorola made 040-060 upgrade kits which only had a PGA to PGA converter with a voltage regulator on it. Everything else was done by rewiring...

[olegil]

Just found it:
The 68060 has an extra bus arbitration pin, BTT. This is not present in earlier devices. It is used for the 68060 high-speed modes. It must be pulled high with a resistor so it won't be used. It's a bi-directional pin, so the chip will see the pull-up and not use it.

Basically, I guess this means the chip would be more effective with specialized glue logic, but I don't really think any 68060 accelerator for Amiga uses this arbitration mode anyway...

Good luck :-)