Shotcup revolution started in 1963. But not every gun maker jumped aboard right away.
I passed on a Merkel from the '40s or '50s - can't remember. But its bores were both .720. Chokes in both barrels were .050 under. My 1902 Sauer bores are .722. I don't see anything unusual about your measurements. Until you decide on opening the chokes vs thinwalls, getting useable patterns for close stuff will be simplest with spreader discs. You can load them yourself or buy them in factory shells. If you load them, the gist is basically to throw 1/8 oz less shot, place disc atop shot, continue finishing the shell - not too big a deal.
Going with fiber wads will generate more open patterns vs shotcups, but usually not as open as with spreader discs. There is also the shot scrubbing and attrition to deal with. More work than I would bother with, unless there were compelling reasons to use fiber wads. I'd rather scrub out plastic than lead, JMHO.
Sam
