I think once you get a well in hand, and thread together a tee and a reducer/adapter for the well, you will see what coaledsweat is pointing out. As long as the well isn't choking off the flow, it should do fine, a little extra room for the water to flow may be better. Just don't restrict it to less than an unobstructed pipe.
I don't have any of the 'gook'
for any of my aquastat probes and wells. Is there a high temp heat conductive product available,, could I just use some other product? I have taken many apart, and have never found the heat conductive grease or gook. Any ideas?