myself if its a full stock , then i would dove tail in the correct under lug to the barrel and then drill for a stirrup type attachment .
If it’s a half stock then I would either build or by the correct front swivel .
This would require a whole ne w RR thimble which includes the attachments
TC often pu these on their rifles . You can get them through ToW for about 8 bucks ..
If you have some ability with metal working tools , you could also eather make one like the TC OR build a mounting that would allow the attachment to clear the RR . As to if the Under rib strong enough . I would say in most cases yes . . But adding an additional under rib screw will help support the attachment if you positions to far away for an existing under rib screw .
If you have a deep under rib that soldered onto the barrel , then a stirrup type swivel can also be made and mounted through the rib , in a location that when laid flat , will always come to rest on a RR thimble . That way you never have an issue with it blocking the RR