it sounds very fun and cool, and i would be very interested in one as a fun backing gun. however i think it is not very practical since you can already get takedown lever actions using tubular mags(with the benefits that brings) in the classic revolver calibers such as 44 mag and 357.
I do think the idea is interesting but i think the .45 may not be the best caliber for it. Maybe think about using the same idea based around the 30 carbine and using m1 mags. This would allow a flatter shooting cartridge better suited to a rifle and would help to bring a cartridge to the lever world which would fill an interesting gap left by the apparent disinterest in manufacturing .327 mag levers.
I think the 45 would definitely be an interesting place to start for this kind of gun though, and would be similar in cool factor to one of those Delisle repros. And if you could get it in 9mm and 40 with some very easy to find magazines then it would make a very fun woods gun.