Substituting for the 9.1v Zener diode in the Krankosaurus

[solderfumes]

I'm planning to build a Krankosaurus, but my local electronics shop is out of 9.1v Zener diodes.  Just wanted to check that I can happily substitute 8.2v Zeners into their positions.  Do I ever need to worry about that being a factor when using any typical guitars/pedals?