For amps, Fender generally used combos with open backs. Marshall used closed back speaker cabs. Fender/Gibson guitars guitars sound great through either set-up.
Open back cabs are not design critical. You can make the cab any size & shape -- as to height, width and depth -- that fits your convenience (and is stable and won't fall over!). Closed back cabs are sensitive to size and shape, including internal volume. This called Thiele parameters. Ideally this should be matched to the published specs of the speakers to be used. Info is available online; Eminence speakers I think has info on its web site. Or plagiarize from an enclosed 2 x 10 design that you like.
Agreed. Most vintage utility tens and twelves were designed (mostly trial and error) to work more or less in a two cubic foot box. They didn't have T/S parameters. Speaker design and measurement were in their infancy. Nowadays, If I was to look for a speaker to work well in an open back box, I would look for a speaker with a Qts of .7 to 1.0 give or take. This will allow the response to roll off smoothly around the resonant frequency (Fo). A lower Qts will sound thin and anemic as the bass rolls off quicker. A Qts above 1 will start to sound boomy and unnatural. These are some rules of thumb that work most of the time. YMMV. A woofer tester and some box modeling software are necesesary for accurate results. Golden triangle dimensions are also usually ignored by guitar box designers. Have Fun!