There's obviously only so much you can do (lowering the saddles) to try to bring the strings
closer to your pickguard and the neck PU underneath, so I understand why you're turning
to a high-output PU.
However... you will possibly have to shield the heck out of the PU cavity so that increased
PU sensitivity doesn't lead to noise. Furthermore, while you may get enough sensitivity in
the neck PU to clearly pick up the highs, the lows may come out murky --which is precisely
what you DON'T want from a neck PU, kasi nga the bridge pickup is already very bright,
and profits the most from balancing with clear lows from the neck PU. I am generalizing,
because I don't have direct experience with sub-pickguard -mounted Artecs.
Older tele PU cavities can be a little tight (with some variation in dimensions), so...
the neck PU cavity will almost certainly need to be reroutered: kasi you'll need ways to
securely anchor the neck PU (with your new Esquire guard off limits to the PU screws);
and because I don't think a typical Tele neck PU cavity in a Tele is quite deep enough to
host a super-lowered PU.
Reroutering is a serious mod, leading me to the real problem:
If the guitar is old (meaning old enough to have value for being old), reroutering the neck
cavity will harm its value. The most prudent (least harmful) mod might be to go for a proper,
authentic Esquire harness: bridge PU only, with an unaltered, empty neck PU cavity hidden
from view.
JM2.