You lucky SOB. My condolences to your GF. You better treat her right. I have a 2000 Busa that sat around for about 2.5 years as I had to have brain surgery and wasn't allowed to drive or ride while on anti-seizure meds. The fuel tank got a lot of surface rust inside I suspect from the Florida humidity (Jacksonville, in my garage) even though I would crank it up and run it up to temp every month or so with stabil in the fuel. You may be lucky if he stored it with ethanol free gas in it and stabilizer. I would definitely drain the fuel anyway, just prop the tank up with the prop rod under the rear seat (in case you didn't know. Clamp the hose coming from the fuel outlet/petcock near the tank and remove it from the pump module. Put a shop rag under the hoses (on top of the transmission) to keep gas off of the chain first. then with an extension hose you can drain it into a gas can. If it doesn't smell bad like turpentine or a sweet smell then you could probably run it through your car if you drive it enough to burn it out. To change the fuel filter is no easy task, you have to remove and disassemble the fuel pump module to get to it. But it's right under the end cap. You'll need some o-rings if you do it too. If it gets to this point, I hope you have a shop manual. I had to gently pry up on the fuel injector rail to get the socket on the bolts that hold the pump module bracket even with a 1/4" thinwall socket, but be gentle it's plastic. I wouldn't bother with it unless the tank has some rust inside, you can always change it later if it bogs when you rev or accellerate, to get the old gas out of the pump module just cycle the key on and off a few times and it will return to the tank and bring fresh gas in. Same with the spark plugs unless they were scheduled to be changed by mileage anyway. There is a pressure relief screw on the high pressure hose fitting on the pump module to relieve pressure from the fuel rail. Grind the tip down on a phillips screwdriver or driver bit to make a makeshift JIS driver (Google it for explaination) for the screws. The rest is just going through the maintenance schedule, oil, brake fluids, coolant, chain lube, tires if needed, check the brakes for sticking. Yes, as someone else posted check the air filter for rat/mouse living quarters and a battery is probably a must. While you have the air box off maybe shoot a little marvel oil or motor oil down the intake ports to lube the rings on start up.
My 2000 had an issue with a thick buildup of gum in the throttle bodies so I started using SeaFoam fuel additive and it has removed it all from the intake ports and backs of the valves, it was THICK. The throttle was hard to open and would stick open. Remember the stand has to be up to start it if not in neutral. If you've never ridden a really fast bike be careful, they do 90 mph in first gear, it's easy to do some serious speed, you don't just whack the throttle open on these, mine will usually either stand up or spin the rear wheel with full throttle.