[RETed]

I wouldn't hesitate to use either unless you're looking for a long-term motor lasting 200k miles?
Surface rust you can knock down with 1,000grit sandpaper and liberal use of engine oil.
Pitting is minor - you'd get minute blow-by, but like I said, you're not building a long-term engine.
Even the corroded water jacket is normal.
The seal is the primary component that seals off the two sides.
So as long as the "wall" stays intact, it'll support the o-ring no problem.
I'd say that as long as you see some kind of horizontal surface, you're still good - again, I stress that this is not for a long-term engine.


-Ted