The value of C1 was 10uF however that is a ridiculously high value for a coupling cap. Probably because that is what they had in stock at the time and wanted to use them up. Since that value would not limit Bass response it wouldn’t matter.
The point is if you are using for Bass guitar you do not need to go higher than 200n (way below the 10uF).
You will notice that all other builds list 100n which allows more than enough Bass frequency through for even a de-tuned guitar or Baritone.
So as long as you have an extra 100n or 200n or anything close that is completely fine.
In no way is there a need to have 10uF. It is just a coupling capacitor.