I have the Optima , also , ... and I would not hesitate to put the Nikon scope on it. If you don't want to put the Omega on there ( and prefer something cheaper ) look into the Nikon Prostaff. If that is not to your liking, check out the Vortex line of scopes. I have a Vortex Crossfire ( 3-9x40 ) and it has nice glass.... But as I do own a few other name brand scopes ..... I own about 9 or 10 Nikon Buckmasters and Monarchs.... Great quality for the price.
Look at
www.theopticzone.com for some of the best prices going on scopes.
MET