Do you mean a link as in 0.5"? or do you mean one inner and one outer (1"). I thought you could only attach an outer to an inner link so surely you would have to add 2. So if its just one link too short (0.5") I'd try it first on a stand then if that seemed ok I'd ride it round the block.
Having said that, I'd size the chain with the large large cog method. See what the chain looks like with that method as you fit it.