[Arran]

A single ended type 47 is probably comparable to a 42/6F6 in terms of power output. I repaired a Canadian G.E J-82 some years ago and it had more then enough power output to fill the room, maybe 3 watts worth. The J-82 is roughly equivalent to a Philco 70 performance wise, maybe somewhat better since it has AVC, with a much better sounding speaker though. The 90 lowboy will probably sound better with that 10'' H series speaker then a cathedral with that stiff "Pie Pan" speaker they usually come with.
Regards
Arran