If going 42 mm or larger in objective size you'll need high rings with Leupold. If you have a 44mm scope now and wanting med rings check out Warne. I have 2 44mm zeiss in med warne maxima rings and bases. (1 QR and the other fixed)
Warne andLeupold DD's have both been excellent from my stand point.
I should note I don't own an omega so I may be wrong but I have yet to find a rifle where leupold meds would accomidate the larger objectives.
My buddy has a 3-9x40 Zeiss Conquest on his Omega setup w/ alow dual dovetail Leupold base/rings w/ just a slight clearance... So I would think that the 44mm might get away w/ the mediums... but it all depends on the actual diameter of the scope.