Even if he wasn't in Chicago, it was easy enough for the dealer to order any configuration the customer wanted. They could even substitute items with what they had in stock. Ludwig most likely didn't stock any given configuration in big box. Individual drums and parts would be pulled and/or assembled from stock. I know that there are people who have kits with sequential serial numbers, but I suspect that is not the norm. If Ludwig assembled ordered kits from parts and badged then at the time of assembly, that could account for the numbers being sequential. There are plenty of pictures of WFL and WFL II standing in front of huge stacks of raw wrapped and painted shells in their warehouse and there are other pictures of stacks of finished drums too.
I've thought of all of this you speak about for decades now.
For sure how I thought how cool it could have been to walk into either or both the Ludwig or Slingerland Plants at the time, those fabulous 40's-60's.
And having "hung out" at Frank's Drum Shop in Chicago in their heyday, '65-'70, you cannot imagine the amount of drums and percussion instruments I have laid my eyes on.
Sets stacked to the Ceiling, equipment of all sorts coming in, and going out. The large amount of commercial equipment, used for whatever, sound effects-traps, Gongs that stood taller than me, you'd need 3-4 strong guys to carry it.
Without a doubt, Maurie Lishon could've got you anything you wanted!
He sold me my first set, 64 clubdate in pink champagne, festival 5x14 snare.
At 6 months my teacher Phil joked and said I was already better than Ringo! LOL.
Phil (Stanger) was a good teacher was why, and was a "hard teacher" as well.
I think I learned a little self defense, as you often got jabbed in the ribs with a stick. Was like that Mountain Dew "Chinese Slap Master" Commercial! LOL
He'd reel you back in though, he'd take that piece he required you to play, and turn it into Beethoven's 5th. Then sitting there playing one handed rolls for days. Yep, he'd make your jaw hit the floor.
He made you say "OK buddy boy, buckle down now, don't waste his time, or yours.