If you're going to use the drum lid as the smoker lid, then I'd definitely go with the lever lock. That way you can keep the ring and use it to lock down the lid during cooking. It will give you a much tighter seal. If you used the bolt ring, it would be a much bigger PITA.
That being said, I've seen guys who've take the bolts out of the ring and just used a spring clamp to hold it in place.
But if you've got the choice, go lever-lock.
Pro Q Frontier, UDS (Little Red), "Turtle Drum" UDS, CG Gasser KCBS CBJ#61160