Just a thought, and others here would know better, but if you are doing only a partial refinish, I would think it would be best to go for the same material as the rest of the neck to avoid compatability problems. I suspect that a Squire neck would be some kind of poly, not nitro. A second consideration is how long does your friend want to be without the guitar. Nitro takes a long time to cure compared with poly and if you don't let it cure the finish will be gone in no time.