Hi Jack,
Would say that there is something mighty wrong if your bike is that slow, would do a complete service on it if I was you, check the points, timing, valve clearances, cam chain adjustment, carb settings, air filter, basically everything. I got a very good F2 manual from David Silver spares, it is not a general CB750 manual, it is a dedicated CB750F2 manual, give them a call.
Cheers
Den