I've never surfed the East Coast but what I see online seems shorter interval, quick and hollow. I would think shorter and more rockered than what goes in California? But you've been there your whole life and shape boards. You don't have an idea?
ps that is an insane barrel you linked...the water is not brown. Florida?
Online is most often a million photos of one-and-dones on the Jersey Shore and Hatteras, so the surf tends towards the howling offshore hollow, and the South blow pre-frontal chocolates the water up. These places aren't exactly the East Coast's (surfing) population centers compared to Rockaway/Long Beach, VB, Wrightsville/Wilmington, and the Florida cities/towns.
Quite a few East Coasters have detailed opinions on the first step up from fun+ wave shortboard. Answering OP's nuanced question about specific width in semi-guns? I can tell you my 6'10" can get in, down, and bottom turn like a bat out of hell, and I've had it fifteen years. I've ridden my 6'8" once in four years, and I can tell you it gets in, down, and kind of bounces/porpoises a disconcerting amount.
Ask us about vac-bagged EPS for chest high beg-Inner bar. 6oz 7 footers? It feels fast and heavy. The finer points of turning/performance as it relates to width? LOL.