[Arran]

I would be inclined to go the filter choke route, unless this is just a temporary substitution or for testing purposes, what you need to be concerned with is how many Henries the choke has, or the DC inductance, but I don't know if the Philco service info of the time gives this, probably just DC resistance. I'm not sure why you bring up whether the set has a single ended output or push pull output, it doesn't matter as both sets used the same speaker with the same field coil, the difference being in the output transformer that was used. If you want to go cheap on a filter choke, or can't locate one, you can use the primary of a small transformer, like a door bell one, maybe it isn't 100% correct but it does work.
Regards
Arran