Check this out:
http://www.emulation.com/catalog/off-the-shelf_solutions/production-test_adapters/upgrade_motorola/It's an interesting adapter which allows easy
conversion from 68040 to 68060...the voltage
regulation etc. are all done onboard the adapter.
Too bad it's $300 (but maybe the price is
outdated?), otherwise it could be an easy upgrade
option for some '040 turbocards.
It also makes mention of a "68040V", apparently
a 3.3v '040.
-edit-
From the site:
Compatibility Issues:
For your system board to be compatible with the S68060-2, a few conditions need to be met. The skew between leading edges of the BCLK and PCLK signals should be no more than 1ns, and the 68060 should not have to perform bus snooping.