All the ones I've got/trying to sell have both a setscrew (for dovetail fitting) and two holes for standard ASA bottomlines.
What you will find though, is that if you have a bottomline which angles away from the grip rather than a duckbill style one, and you mount it on a medium to long length drop, you will find your bottle will be down by your chest rather than at your shoulder... I think that makes sense
Cheers
Ray