^^^
I've done it before with prop versions of the same gun, and I probably wouldn't do the whole John Wayne flip thing. Aside from the fact that it'd be easier and faster to work the lever by swinging the gun downward and back up again, the flip is hard to do if you're not a big guy with long arms. That, combined with the fact that I'd probably have to custom make a lever with a wider hand guard, and that any kind of action working other than traditional is likely to put a lot of wear and tear on the gun, makes the whole one handed operation kind of silly if you're going for realism. Badass in Stage Coach and Terminator 2, but you wouldn't see that kind of gunplay in Unforgiven, which is more what I'm going for in the more recent work I've done.
The SxS would most definitely be cheaper than the 1887, and much easier to find used, which is why I'll probably end up going for one of those. And yeah, in the hands of a trained shooter, a double barreled shotgun can be as fast or faster than a lever or pump action, even when it comes to reloading and firing more than two shots (search Youtube for Cowboy action shooting if you want examples). Good call on Browning though, a while ago I saw a documentary about the evolution of the shotgun and had forgotten that he'd designed both the 1887 and the Winchester 1893 pump.
I wouldn't mind owning an 1887 shotgun eventually though, so I suppose in the end it'll come down to which gun I find for an affordable price that meets my needs first. I already own a SxS coach gun, I just don't really want to cut the stock off, but I considered making new wood for it to solve that issue. I do some gun smithing here and there in my spare time, which incidentally is why my character in Mad Nation often gets to use some pretty unique weaponry.
