I'm currently fixing up a friends Peavy Grind 5 string bass. It has a broken machine head which needs replacing. The guitar spec says the machine heads are 19:1 ratio and im struggling to find a replacement one. Would it be fine to use a 20:1 ratio?
As long as the hole depth and dimensions match up with the previous hole, you can get any bass machine head regardless of the ratio. The ratio more or less just tells you how accurate you can get while fine tuning the string.