Hello, I can't find the 1N270 diodes, can I replace them with the 1N34A?
The forward voltage is a little lower on 1N270.
Every other Ge diode you could get your hands on would be a better substitute. Otherwise, use a Schottky diode like 1N60P or BAT4x. Schottky diodes are cheaper and the difference between them and germanium doesn't matter in this context.
That said, I don't know where you're located, but Smallbear has the 1N270.