We are mainly working with opinions here. Mine is that with a collector-type mower such as yours it is always best to have the original engine or an identical replacement. This is especially so when it had a B&S, because those old ones were very good engines. However a pre-Chinese Honda is an even better engine, so if you are going to depart from original specs, that is a good choice. I have never seen a Robin engine so I can't comment on those.
