[Arran]

The Ever Ready B-107 is a British market battery, it's likely that the original was similar to the blue and yellow Philco battery. Never had many problem with voltage regulators, but there are more then a few circuits and plans for battery eliminators online, given the current draw of 1940s era battery tubes a voltage regulator isn't going to be run at anywhere near it's full current rating on the A+ side. As a safety precaution you could add an appropriate sized Zener diode across the filament string. 1940s era battery tubes are largely inexpensive, but it's no reason to be careless with them.
Regards
Arran