Strange, I just traded my 707 for an 81-7 from a member on here. The 81-7's housing is the same as the 707 (bass pickup housing) so it's larger than normal passive pickups. That's good that you didn't have to route or anything BD, my friend had to route his Washburn 7 out for the 707 he originally had to replace the stock Washburn passive.
Lazzari: Sign up on SevenString.org and ask there, best advice I can give.
~006