I sounds like he's talking about 1/2 track mono (half width mono in each direction) at 3 3/4 ips. I think it really depends on how high a quality playback you need? If it's spoken word and you're looking to do a digital transfer than you could use any 1/2 track machine and just use one channel. At 3 3/4 ips you won't get super high fidelity in most cases. If fidelity is totally irrelevant, you could play back one channel at a time with a 1/4 track head or 4 track. The only configuration that won't work is a full track mono.
For the best sound, you'd need a 1/2 track mono playback head but outside of archivists, it's a pretty rare bird. If it's an important recording, it may be worth sending it to an archivist to have a top notch transfer made.