This is a cool project!..:-)
But i agree with alexh, try to get an MC68060 with the 1E41J mask instead, a much better cpu.
There is one more thing about the Blizzard 1240.
I know there are some people who has upgraded this card to 1260, but will only changing the cpu really do it?
What about the firmware, this should be upgraded to, for optimizing the cpu?
And another thing, both the Apollo and Blizzard turbo cards have multilayer PCB.
You have to think twice about how to desolder the cpu, if you use an ordinary desoldering station, there is a big risk that you will destroy the PCB.