The lumber they used for structural members (huge, 8x10ish boards, very long, all around where the foundation met the house; joists; et c) or for other parts that were never meant to be seen, like floor underlayment (which was a bunch of ordinary boards laid diagonally, so they wouldn't match up with wood floor boards laid atop it—not plywood) would probably have gone to veneer these days. Knot-free, perfect stuff. Much of it's likely nearly impossible to get these days at any price, in the same size and quality, short of salvage from houses like that. I never got much of a look in the walls, but it was 2 stories plus a full-height floor for the attic (need that for temp control, in the days before air conditioning) and was "balloon" construction, which means they used a whole bunch of boards 2-3 stories high to frame the exterior walls, which, again, probably nearly impossible to find these days, straight and strong enough to do such a thing.