High impedance loudspeakers
Making high impedance speakers is difficult.  Take apart some old broken speaker and you will see the wire of the coil is already very thin and long if you uncoil it.  To get higher impedance, you'd need more turns, which means longer wire, which means even thinner if you want to keep the mass the same.  Since the coil of wire has to move back and forth, keeping its mass low is important to good performance.

All these tradeoffs conspire so that it is impractical to make speakers with high impedance and good performance and reasonable cost.  You said yourself the 800 &Omega; speaker wasn't that great even by 1958 standards.  There are probably good reasons for that.

As Andy said, go use a audio tranformer with the right ratio.  These used to be a lot more common in the tube days, since tubes don't go to really low impedances well but do handle high votlages well.  Tube amps therefore put out a high voltage high impedance signal directly, which was then converted by a transformer to a low impedance lower voltage signal more suited to driving a speaker.  Since a transformer was in there anyway, it often had a center tapped primary to allow two identical circuits to drive each direction actively.  This was useful because there is no PNP or P channel equivalent tubes, which are inherently N channel only.

Today we use transistors which can go to very low impedances directly, operate well at audio power voltages, and come in complementary positive/negative versions.  As a result, most audio power amps today drive the low impedance speakers directly without a transformers.

Audio power transformers are still available today, but this is one of the few parts you can usefully salvage from a old tube audio power amp.