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That will work fine as Old one eye. It has all the bits required. The codex says just before the army list I think that we can convert our own models to show unique units like Old one eye or the Swarmlord (with our own background etc). As long as our opponent knows what it is.
I think that because Old one eye is a very nasty Carnifex you could make it look meaner. Beside a normal plastic Carnifex this thing may not look the part, even though it's the same size as the Old one eye model. Try adding more spikes, blades etc and make it meaner looking. Also there are some very obvious mouldlines on those claws which you should remove because it lowers the standard of your model alot.