My prediction would be: not well. Depends a bit on the table and the break format. Winner breaks and non-gaffy table, an 800 fargo will probably string 3-4 racks and be a threat to run 5-6 as well, any time he comes to the table with a makeable shot. He'd likely adjust his game a bit, to make sure he doesn't leave you anything. Remember that he is about a 50% to run out from a hooked position.
I don't really like your chances unless you are 700+ yourself. An 800+ fargo is an entirely different beast from most other players. Insane shotmaking, Godlike kicking, flawless strategy. There isn't really a lot you can do against a guy like that, unless you string racks every inning. They can run the set out at any moment and will put insane pressure on you.