Barrett - Thanks for the detailed reply.
You are correct in getting sustained downhill in this area. I quickly max out the gears on any downhill and lose the ability to pick up some speed. Still thinking about various things to try as I can buy just the large chainring. They are available in 50, 52 or 53 on ebay in the $50 and less range.
Think I'll buy a 50t to swap out and see what it does.
Al