Curt's point is important: anything that costs money, upsets the production line, or adds parts will be vetoed by the accountants unless it's actually necessary.
15 years ago in an unheated poorly lit garage with the head laying on a messy work bench and using a hand held drill motor I did the deed.That was before I knew of anything of 12 degree angles.So the god of dumbness protected me,I drilled directly into the water passages no problem.
I know of more than a few guys who have drilled steam holes in a 235 head and no one mentioned anything special.
Now that I know this I will be sure to aim the drill towards the port side to be on the safe side...A good tip.......
