I don't know much about training for Epic type events, but taking a periodised training plan approach you would have the following phases: foundation (base), build, specialisation, taper, race. You clearly have a solid foundation in place so the goal for the phases would be: build: raise ftp as high as possible - i.e. build aerobic capacity. specialisation: for the epic would be long rides sub-threshold to get used to the sheer volume. I don't think the Epic would require huge anaerobic capacity work. taper: not much for an event like the epic. This I would guess would look like a "reverse" periodisation plan i.e. work on improving threshold first, then add volume at that higher threshold so that you are accustomed to the volume when you get to the race. Doing to much volume first would probably be hard to sustain. Frank Soll (Bicycle Power Trading) would probably be able to give you plenty advice - he won the Masters cat a few years back.
