Non-businesses can ship optics to Canada but businesses need an export permit, I've shipped a couple scopes north with no problems, just mark the customs declaration. The discontinued Ultra base works, but the Weaver #82 will work just as well for the shotgun scope, you can always cut new slots in it if needed, that's covered in the FAQs in the modified weaver base link. There are only so many bases made for an H&R, they're all in the FAQs, some have mounted small shotgun scopes with both rings on one side of the turret saddle instead of one ahead and one behind.
Tim