yup the super rods will fit, bottom end is the same as the K. I am running the super rods and they are good quality. Not sure how much money you are wanting to spend on this build but having the crankshaft lightened and balanced makes for a smoother faster revving motor. Definately need to get an adjustable cam sprocket to dial in the new cam. The F2 already flow much better than the K heads and they come stock with larger intake and exhaust valves. If you want to make power you need to have the head worked on, that is where the 750 makes its power or lack of power if you run a stock head. At a minimum I would have guides and a valve job done provided the valves are in good shape...along with good valve springs. Ape and Cycle X both do porting on the 750's...I hope you have better luck getting through at Cycle X then I have the last couple of months, not sure what is going on but I cant get a response back from email and it took 4 calls to get an answer back. Still love there parts but I am losing faith in the customer service at the moment. But yes I do suggest having head porting done but be prepared to shuck out $800 or so for porting then the guides, valve job on top. Yes a good head costs some $$$ but as the saying goes...speed costs money how fast you wanna go??
i am in the same boat for the carbs. I really need to get some good aftermarket carbs for my 970 build. But will be going after a set of carbs like yours has stock. They are slightly bigger than the early ones. Money no object go for the Mikuni's cycle X is selling, very good carb. You could also have Cycle X bore and rework your stock carbs to get some more airflow, they do offer this.
I have some good pictures in my galleries of the motor internals I have and will be putting up more ones I start to get all my parts rounded up and bakc to me for my 970 build.