A lot of newer output transformers will have 2 or 3 taps for the speaker, 4 or 8 or even 16 ohms.
You can match just about any speaker or combination of them to these transformers.
Two 4 ohm speakers in series ( phased properly) will be 8 ohms just as in reverse , two 8 ohm speakers in parallel ( again watch the phasing) will be 4 ohms.
Look up a Hammond 1609.
Good luck with the restore.
Regards John G.