Classic Bus overclocking?

[Gulliver]

Yes, the bus can be overclocked but then you would face a few incompatibilities with some Zorro II cards that rely on this old timing.

Just to name a few examples:

-The Elbox Winner Zorro IV busboard (a Zorro II busboard) had a fast Zorro II mode  on some slots. The CyberVision 64/3D cards that were manufactured by DCE (not Phase 5) can take advantage of this feature and also the famous Deneb USB+flash rom card.

-The MacroSystem´s DraCo has five Zorro II slots that operate at twice the speed of the traditional Amiga Zorro II slots and can make use of most of the Zorro II cards that were made.

So yes, it can be done.

[Gulliver]

Drago's zorro is not 2x faster. Speed is about a 4.5mb tells google.

You should not always believe what Google tells you.
I have two DraCos at home and Zorro II slots can be run twice as fast. Of course this depends on the particular card you are using, because the card itself may be the bottleneck.