I don't think engine internal problems are likely, but you may still have bent the end of the crankshaft (though it isn't easy to do that). If you have, the mower won't be worth fixing unless you can find a junk one with the same engine. Moving an engine from one mower frame to another is dead easy (providing the frames both had that same engine type originally), and even moving the crankshaft from one engine to another is worthwhile if you enjoy spanner work (it should take well under an hour), but the value of that old engine is vanishingly low. However if it's just a bent blade plate, you can practise your panel-beating skills on it for no cost and with no risk of damaging the mower itself.
It's all fun unless you spend money on it - then you're likely to end up feeling foolish, since you could buy a newer, better mower for very little.
