Oooo ooo oooo and you're removing the fretboard with a hand saw. oooo ooooo oooooooo. I'm hating it for ya. I would use a band saw if I were you. Borrow one or find someone who has one.
Turned out fine in the end. What you don't see in the photo is the 2 steel rulers cleverly clamped to the sides of the neck so the saw will not get off course. The whole shebang is also clamped to the shed so that it will not wiggle. A slight cleanup with a hand plane was all that was needed to ready the neck for the new and correct fretboard. Happy ending, it plays and sounds great. Check the vid if you want