OK so it looks like the consensus is pressure washing and opaque stain if it doesn't clean up good.
I looked at the perma-chink web site and I will be contacting them for a sample of a couple of their restoration products. While expensive, but still considerably less than contracting it out, they appear to get everything off the wood! If that works I may be able to go with a lighter stain!
Thanks for the Info All. It'll be a big job but I know it will look great once completed!