http://newtechnologyproducts.net/aluminum_repair.htm

Tom

http://www.welding-advisers.com/Welding-aluminum.html

More information to digest.

Tom

There's nothing wrong with your case. That's totally normal. If you want to, you can epoxy the external portions for oil leak prevention.

True enough. Porsche used epoxy on the cam boxes where the bosses are machined through. Also on the back of the engine as well around more machined/plugged bosses.
Check out the "Rebuilding Guide" book.
When I re-did my cam box seals and chains we mixed up JB Weld and applied it to the areas in question after cleaning the factory epoxy off of them. No leaks whatsover.

Tom