Measure full scale length from inner side of nut to high E bridge saddle. Presume the kit comes with standard Gibbo scale which should be 24.75" which equals 628.65mm. Half is roughly 314.32mm so that would suggest your measurement to 12th fret is slightly out?
On my EX-1 it has a set neck and I spent ages worrying about scale length that once fully set and well cured only then did I then notice neck PUP mounting ring would not fit. Bummer but better having an axe that you can intonate and is in tune all the way up the neck than one that looks aesthetically pleasing but sounds out of tune.
I ended up top mounting the PUP's as a way around the usual setup. Looked at cutting various neck mounting rings made from timbers (Rosewood looked good and blended with end of fret board) through to metal or chrome ones. Was not confident I could make it work and went top loaded instead.