I doubt you can actually make a YF-17 out of that kit. The YF-17 was a Northrop only project and was physically smaller than the F-18 which was a joint Northrop/McDonnell Douglas project. Whole new airplane, similar to the F-18E/F morphing out of the F-18A/B/C/D.
Hasegawa kit SO23:5800 is supposed to represent the first 5 development airplanes. It's also 1/32 scale. I has the development decals also, of course.