1N4148s will work fine in place of the 51V zeners in the Disarray. Save your 1.8V zeners for a circuit that actually needs 1.8V zeners.
Another zener question, Derailer (Ethos) : 1N4678 - can't find that one, it's a 1,8 V … what can I use as a substitute ?
I have 2,1 V Zener , would they work ?
Ah, I see - there are some in the PedalPCB store ...