Okay so I bought an F1 with a rusty tank. Anyone put an f2 tank on an f1

 

Can't offer any practical experience, but I can offer that I couldn't find a definitive answer when I considered this last year. They are a little differently shaped along the bottom and front edges, but I think it might fit on the frame OK. Not sure if it would match up with F1 fairings very well.

If the F1 tank just has surface rust inside and is not completely rotted through you might consider the electrolysis method of derusting it. It involves filling the tank with a washing soda solution and inserting a steel electrode into the filler hole and the solution, then connecting a battery charger across the tank and electrode. In a few days the tank will look like new inside.

 

F2 tank will likely fit with a little tweaking. The mount by the seat is slightly different.

The tank shape is different both on the surface that rides along the frame and the back area that lines up with the tail fairings (there are curves that are not on the F1).

This means that the F1 fairings will not fit properly to the F2 tank.