Hello Bruce,
I'll throw in my two cents. I'm fond of tar paper and I'm convinced it's a much better solution than Tyvek, particularly where you don't have a lot of moisture coming through, as you do in conventional framing from all those fiberglas batts. Synthetics don't hold up to UV as well as tar paper, with all the knot holes.
And for what it's worth, I heard of a fellow putting board and batten with horizontal furring strips beneath that had been run across a table saw every foot with a 1/4" X 1/4" dado to increase air flow. Seems like you might accomplish the same in less time with a router, laying all your batts on the flat and buzzing four feet at a time or so.
Good for you for trying keep the old boards.
Zach
