Here's the rule I found on the AO Smith site: if the old motor's HP x it's Service Factor (SF) equals OR is less than the NEW motor's HP x SF, you're OK. If the new motor's multiple is LESS than the old motor's, you are NOT OK, and will need to replace the impeller.

Looking at the photos you sent, what I'm seeing is:
OLD => 1.5hp x 1.0 SF = 1.5
NEW => 1.0hp x 1.5 SF = 1.5

So, I think you'll be OK. About any of the other, I'm not sure.