only time I would replace the clamp is if it stripped from overtightening or something.
rather than go oversize (stainless screws are very expensive) , you can just fill the holes with marinetex or a marine epoxy available at any hardware store, then set the srews as the epoxy is about 3/4 cured.
Ayuh,.... I'd think if ya had it runnin', 'n the waterpump worked, pumpin' water,...
The Entire coolin' system would be as suspect, as the transom seal....