After seeing the line drawings of your engine, I see what you mean. Serious torque might do some serious damage!
If your engine has the same port side setup as the GM, you might be able to do the same partial improvement that I did before you can get to replacing the front zinc. I replaced the 1/4" pipe thread plug just below and forward of the starter (23873-020000 on the Yanmar diagram) with a Martyr CME0 Z pencil zinc which I had cut back to about half length. Better than nothing. I actually ran across this by accident last summer when the stock plug failed and started leaking.
