On Mon, 12 Jul 2010 19:52:37 -0400, Bill wrote:

I shouldn't have the least worry about threading a 12-2 romex cable
through 3/4" holes, and back through the same holes, should I?

You should be able to use 5/8" holes.

Nothing else will be in the holes. The issue that bothered me (a
little) is knowing that both cables would always be used at the same
time. I'm going to try out my new auger bits tonight--starting off by
making some bit props to get the holes lined up..should be fun. : )

One thing you might do is put the wire on a stick so it comes off straight,
without kinks. It makes it a *lot* easier to thread through the holes, if
it's straight and not all loopy.