I've gotta call you on the 50K comics fitting into four big boxes ... unless those "big boxes" are shipping cartons for hot tubs, LOL
I earn my living running a machine which binds saddle stitched publications, and have a pretty good handle on how much volume 50,000 comics would occupy ... sounds like
three or four large pallets, stacked about 4' high.
Oh, many times I could kick myself for selling my collection. About 30 years ago, mostly DC Comics purchased from the mid 1960s to mid 1970s. Sold to a coin/collector's hobby
shop sort of place when I was despirate for money. I think they paid me something like $35 for the lot. Sadly, I knew even as I was doing it that I would always regret it. But, what can you do?