Loose rivets/ smoking rivets

I need some advise on how to fix a few rivets on my right rear wing spar. About 18" outboard from the fuselage on the right wing. The PO didn't drive them effectively and now they are loose. I don't have access to redo them. I was thinking of drilling them out and putting blind rivets in their place. My questions are:
What size blind rivet diameter and grip length? (I don't know the thickness of the upper flange of the rear spar + skin thickness. )

Are the blind rivets as strong as solid rivets of equal diameter?

Is there better option other then blind rivets?

thanks for your time and suggestions,
Rich

If they are the top skin to rear spar rivets, they should be accessible. All of those rivets are aft of the spar (flange is aft). If they are skin to rib, you can replace with the MK-319-BS.

I can see them thru the bell crank access panel so they are definitely on the inside of the wing.
Thanks for the response.
Rich

What grip length would be needed if it's riveted into the read spar?

You are right. They are accessible if I remove the flap. Thanks for the info.