will echo the comments about b-squares vs sportsmatch.
the b-squares will only give you a certain elevation adjustment because they rely on the rotation of the shaft to do so, which can only fit in every 180 degrees... the 2 piece are easier to setup than the ones, because you can just lift the rear of the two piece off the dovetail, rotate 180, and replace.
the sportsmatch use a grub screw, so with nipped up mounts you can simply just dial in the elevation, and then tighten the mount up and it's sorted... i've got the ones that only have elevation adjustment and I think they're my favourite mount to date.
BFTA/NSRA County Coach
CSFTA Chairman/BFTA Rep