I looked for replacement parts for the second schematic, the BC184-214 combo can be replaced with BC550-560 the BD135-6 could be substituted by the TTC011B/TTB006B combo from Toshiba.
I don't know. Easier for sure. Better? Maybe. I'm aware of the CMoy amp, which is basically a barefoot opamp. Will build one of that too, saw an article about one being built in freeform style and completely encapsulated in resin, it was really cool.
The manufacturer specified 38Ohms impedance.