I have known quite a few horses do very well in corrective shoes at shows up to county level. Personally, I don't like seeing corrective shoeing on show horses because, in theory, if they were as well-conformed as they ought to be (considering that a primary purpose of showing is to select good bloodlines for breeding stock) then they really shouldn't need them.
Some judges seem to share my opinion on this and mark down for corrective shoes; others really don't seem to care. And then there has been at least one judge that put a particular horse of my acquaintance top of the line despite his feet being literally dropping to bits due to laminitis-induced horn issues (in fairness, said animal is a sweetheart and otherwise very nicely put together, but his feet have always been horrendous).
To be honest, as long as he's sound and mannerly I doubt you'll have too much issue with it - worst that'll happen is that the judge will drop you down the line a place or two on the assumption that there must be some underlying issue that justifies the shoeing choice, and even then they more usually only use shoeing to choose between two individuals of otherwise-similar quality.