I've spent the better part of an hour and a half on the net searching,
tried to get into the ABS site which appeared to be down, spend
several hours searching through what manuals I have, but I couldn't
find the torque required for the spark plugs in an IO-470N.

I did find the torque values for about any bolt size you'd ever find
on an airplane (wet or dry) though:-))

Any one have that, or a URL for the source?

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com