Remington 20g. scope suggestions.

[Steelworker]

I just bought a rifled slug barrel for my daughter's 870 20 gauge. It is the kind that has the canteliver mount attached to it. My question is: what kind of scope do you think I should get for it? Also, someone told me that the long eye relief would probably be better for it. I dont really want to spend more than $150-175.

Thanks everyone!