[paulsherwin]

There is nothing wrong with using OC71s in this position. They were intended for this sort of small signal AF amplification application.

You won't get a significant difference in performance by subbing any similar transistor from the Ge era. The variation in gain between transistors of the same type is much greater than the variation between the nominal hfe numbers of different types.

Differences in the performance of homebrew projects like this once built will be mostly caused by different construction techniques or even construction errors.