Measuring from the nut end of the fretboard to the 12th fret equals 12.5", so I need to set the neck so the distance from the 12th fret to the center of the bridge post holes is also 12.5" to give me a 25" scale length.
The neck is a nice, snug fit so I got it close and then tapped it into position using a hammer and a block of wood to get proper alignment. 25" on the money - that will allow for saddle adjustments either way for intonation.
Properly lined up - now I make a light pencil mark on each side of the neck to make aligning after gluing easier.
Let it set overnight and removed the clamps. Me likey...
Next up will be sanding and any necessary surface prep.