Generally speaking, these ears still prefer a two-way horn loaded speaker with a 500 cycle horn, but I believe the EV would be a fun speaker to restore and enjoy. I believe I could easily live with a pair.
Well the Sentry III has a 500 hz horn. Is that the one you listen to?
It's about the same size as an Altec 511 ear ringer ......just not metal and much more mellow..a real nice horn IMO