The newer 527s imported here (allegedly) have a bolt handle that lets most ocular bells clear. I did the Calhoon thing and it worked great. If I get another 527, it'll be a .204 Varmint, with a 6-18x Leupold VX 2, which is fairly compact/light for the magnification; a 4-12 would be even more so. Should clear the turrets okay; www.diproductsinc.com
sells a picatinny rail conversion if you think that clearance is a problem. CZs don't have bases per se, btw; they use 16mm "ringmounts" made also by Burris, Leupold, Millett, Warne, and Talley(?). Americans come with these "rings", but Varmints don't.