I see your "F" is an 81...What year is the donor "K"?
I believe they are different frames but not sure if the parts will fit easily, need slight tweeking of the mounts, or major modifcation to work.
81 Honda CB750C - Current Project
67 BSA Spitfire MkIII - Next Up (Full Resto)
81 Honda GL1100 - Bob / CafeĀ“
80 Suzuki GS750L - Bratstyle
72 Honda CB450K5 - Basket Case
73 Honda CB350F Cafe' (Gone but not forgotten)
Don't wait for opportunity to knock... kick the door down and drag the old harlot in!