Vm 1245/1266

[Electronic M]

In the 60's and earlier power relays were almost unheard of.

Personally, I think you'd be better off replacing the caps on the original amp/preamp chassis. Get a Sam's photofact for it, order caps based on the parts list, and solder them in....When I have the chassis for such a set on my bench I normally have the caps changed in under 4 hours....Can be 30 minutes or less if I'm focused and on a roll (especially simple chassis).

Audio circuits are not terribly picky...If the tubes are good (likely), the resistors can be off tolerance and many things can be a good ways off of ideal, and the effect on performance may not be noticeable.