Done this 2x/season on my 1999 310 since new. The shutoff is in under a panel in the port aft cockpit locker. Sometimes its hard to get enough torque on the racor filter to take it apart; it's held on with two sheet metal screws to the fiberglass engine bearers and the screws may eventually tear through. Use a ratchet wrench or small oil filter wrench and keep your free hand on the filter housing to counter the torque trying to rip it off the bearer. One size will enable you to undo the drain plug and drain any water & crap. If what comes out is clean, no need to prematurely change the filter. If contaminated liquid or particles come out, time to change filter, even if its just a few hours use old. Don't forget the new gasket that comes with the filter. It goes in the top cover of the filter holder (remove the old one first). Always change both the engine and racor fuel filters together. Bleeding is the tough part of the job - many cycles of the lever on the lift pump required. Sometimes you can get away without bleeding all the way to the injectors and just need to get air and bubbles out of the engine mounted filter. Otherwise you need to loosen the injector bleed screw and get air out there too. Be sure to run engine for at least 5 minutes at the slip. A bubble in the system can take that long to find its way to the injector and stop the engine. After 5 minutes at 1200 rpm, you should be fine.
