transom flex

[cooppat]

I am looking at a 1974 20'sf, that has a 1988 175hp black max on it, the transom currently has an alumnium plate which appears to be well done, it has not been raised and the transom has not been restored.

DSCF0004

Should there be some flex in the transom, and how much is acceptable, what should I be looking for as a clear sign that the transom is junk.

I realize I would need to replace it at some point but when should it be done?