I'm trying to remember details from some 21 to 22 fret conversions I've looked at over time...
If I'm not mistaken (which I could be), you're looking at 2 scenarios for the neck swap: both necks will either have the same scale length or they won't.
***The easy check for this would be to lay the necks face to face matching up the nuts and seeing if the frets line up all the way down- if they don't, they're... well, they're different ;-)***
1. If the 21 and 22 are the same scale length then the extra fret is going to be on an extended overhang of the fretboard. In this case (and I think this is the more common of the two) there may be a need to remove part of the pickguard where the overhang rests so that the fretboard isn't on top of the pickguard (not usually designed for that, although yours might be different).
2. If the 21 and 22 are different
scale lengths then you're in for a bit of luthiery- you'll have to determine the scale length and either route out the neck pocket or move the bridge (or maybe just the saddles) to compensate for the difference. Otherwise, you'll never be in tune.
Since the
Warmoth body (super sweet, btw) and the birdseye Mite (also super sweet) are probably both built to a standard strat scale, you're probably just looking at trimming up the pickguard (which is easy enough but would look bad if you ever switched back). That looks like an EMG Dave set, and if it is, they're pretty attached to the pickguard from what I remember. Still, it might be worth it to consider hacking away at a new pickguard and transplanting everything if you thought you might go back to the 21 frets.
Good luck, congrats on the sweet deals, and if there are errors in my thoughts here, others are most welcomed to provide the right info- we're all in this together ;-)
6stringer
