Alvin,
My advice, which is free, is : Don't spend anymore money on it.
You should not in good conscience offer it for sale as a shooter; sell it as is if it is not special.
Someone would buy it for a shooter, like someone with a spare bolt.
It is already mismatched, so another mismatched part will not hurt it in my book, visible or not.
Mismatched is just that and the value damage already done.