I think i get where you're going with that
The only problem i can think of is that due to the design of the chod rig having the lead directly coupled to the leader and the popup able to slide up you'd end up lifting a large section of your main line in the water which might spook a few off, with the zig rig it's a bit like a semi running rig with an inline so your main line is (hopefully) pinned down with just the hooklength raising up. I can definately see some potential from that idea of yours though. Although its kind of doing the oposite i could see with some modification it could make a great surface fishing rig by having the chod rig but a swivel higher up like you suggested a controller float could be attached and a semi-fixed running clip used to attach the hooklength with either the popup or some bread idea being in the event of a main line breakage, the semi fixed clip would give an allow the fish to leave just attached to the hooklength rather than the controller and the lead, also having the lead there would prevent the bait from drifting about too much as is quite often the case with surface fishing rigs