I once had an OMC 28hp ‘SPL’ OB motor where the starter was held on by 3 attachment points off the powerhead, 2 towards the front & 1 point to the side. That side location was a nub or tab as an extension off the block and it broke off (casting seemed porous, like looking at a Nestles Crunch candybar). The 2 existing front bolts were not strong enough to hold the starter due to the torque, as it would pivot away from the flywheel.
Fearing nothing to lose, I cleaned the block area well with naptha and put a big blob of Marinetex in place and let it cure well. Sure enough, just like the Marinetex container said, I drilled & tapped the blob to hold the 3rd mounting bolt. Worked like a charm! Sold that boat a few years later and ~10-years later ran into the boat/motor and its latest new owner at a launch ramp and son of a gun ... that blob was still there holding up its end of the starter!