A 741 OP-AMP is used as the final audio stage, but this could be replaced with an LM380, if you want to drive a small loudspeaker. The ZN414 could also be replaced with the more recent ZN416 IC to provide 18dB more gain. The 741 OP-AMP will drive a 70 ohm headphone quite easily. OP-AMPS make good low power AF amplifiers but they do have their limitations. Here isa crystal controlled RX for 27 MHz.
Crystals are readily available.
A GDO is a great help here. USA CB TX crystals will get you into the 28 MHz amateur band. A 16.5 MHz crystal will get you into the 50 MHz amateur band. A 14.0 MHz crystal will get you into the 70 MHz amateur band. Get the RX aligned to the exact frequency by adjusting the IF transformers.