No, and if this represents your level of electrical savvy, hire an electrician BEFORE you burn down your old house, old barn etc.
When you say "the two 120V wires coming from the fuse box" I'm going to have to assume that you know nothing about how the US electrical system works, and have not bothered to educate yourself on it before deciding that running a connection out to your barn might be just the sort of DIY project for you. That's very concerning.
In all likelihood, if you have an "old house" and it actually has "a fuse box" the service is nowhere near 200 amps to the house, much less running a 200 amp sub to the barn. You might be better served to put a new service entrance on the barn; if not, you should have the service entrance on the house upgraded before trying to provide service from the house to the barn, and you should not be doing that yourself from what you have written so far.
In any case, you cannot use 6-2 to run a sub-panel (you need 3 conductors and ground for a sub panel), and it's 7 sizes too small for copper, 9 sizes too small for aluminum wire if running 200 amps. So again, no, and no.