Sounds like much of the pricey and important work has been performed -- don't let the mileage be of great concern either. You'll never need to worry about the bottom end -- in regards to to the top end, I'd wonder about the valve stem seals and as you metioned, cams. A constant ticking noise is indicitve of this it could be rocker arms. (my scenario) Nonetheless, from your description it doesn't appear to be a money pit.

If it checks out OK with the mechanic, go for it!