i installed the LEUPOLD base #54798 and the medium rings[duel dove tail]# 49916 ,on my T/C encore which takes the same base and rings as ur OMEGA ..no lapping requiredon my installation .i used myDigimatic caliberand measured base to rings than from ring to ring .
ps. my T/C ENCORE is stainless so i installed the 54798 silver base...but the 49916 rings are black matte..
here is a link for bases and rings for ur T/C OMEGA ..
http://www.precisionscopes.com/mounts_by_firearm