I have an old #4 clone (Craftsman) that I've been considering repurposing as a scrub.

1) Are #4's too short and/or light to make a good scrub plane?
2) After cambering the blade, would I just back the chipbreaker off 1/4" or so from the edge? Does blade chatter become a concern with this back-off? Should I buy a thicker blade?
3) Should I just be looking for an old #40 instead?

Thanks for your feedback!