Even if you did find two bigger cans there isn't much clearance between them there to fit, no? Id fabricate an aluminum box for both OPTs together the same width as the wooden case. But then you have to think of heat too enclosing the OPTs, its not too hard to fabricate an aluminum box with a mu metal lining, and some vent holes on the top and along the bottom side edges to get some convection cooling.
What gauge of aluminum do you use? I've got a pair of Lundahls that need covers, because they are just plain ugly.
Seen these?
Audio Transformers • Housings • Lundahl Transformers
I'd form the two left/right sides and top with two bends....
Thank you for the pointers. I will try that sometime.
Regarding the OP’s situation, those big power tubes seem close to the transformers, so the aluminum-U should probably cover the front, top and back of both transformers, with the left/right end pieces in wood. I always like power tube glow reflected by mirror-like metal finishes.