Singapore Hobbies also has a large stock of Hatori headers for rear exhaust OS engines.
As far as bearing life: I'm not convinced that you need to buy expensive bearings. I get at least 350 flights out of the 'cheap' bearings. Over the years I've seen $60 bearings fail just as quickly as $5 bearings (less than 50 flights). Lean runs, dirt and corrosion are the biggest 'enemies' of all the internal parts.
The Hanno is my all time favorite engine...
-Will