Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior
Have the HP and furnace in. Still need to turn up heat and fine-tune in a couple of days. As recommended the contractor did a nitrogen flush on the line set (and brazed with nitrogen too). The 15 year old line set was clean! The contractor did caution though that had there been a burn out, the line set would have been pretty much useless and would have needed replacement.
Thanks, all, for he advice. I have a very good peace-of-mind that at least it was done right and my new (expensive) dual fuel system won't fail early due to reusing a dirty line set.