I assume you know that is a chonda version of the Honda GXV340, and most parts will be interchangeable.
It is unlikely that a starter pinion with a different number of teeth will mesh properly with the ring gear. To do so it would have to have been custom-designed with some unusual tooth form corrections, which would make it a bit gruesome anyway, but more realistically it will have been designed for a different center distance. It might or might not work well enough for a lawnmower - I've known of people doing it with Lister diesel engines and having it last for a while, though not very happily, and of course it destroyed the ring gear eventually. However the length of life expected from Lister diesels is probably about 20 times as long as the life expected from a lawnmower.
