Going from 8 pin to a 9 pin isn't reducing, or am I misunderstanding?
Another option is something that Groove Tubes used to make. They called it a Substi-tube ; the bottom part was an octal base, and the upper part took a noval tube.
The internal wiring rerouted the octal pins to the 12A--7 pins.
They made 3 different ones, to replace 6SL7's and 6SN7's, 6SC7's, and 6SJ7's.
Maybe they still have some collecting dust at their place.