Ruger #1 Varmint .223

Just purchased the above gun yesterday at a show in Mesa AZ. Unfortunately it did not have the scope mounts. Ruger wants appx. $40.00 for a factory set, but I see that Midway has Weaver #85 and 89 that they say are for the #1V. Does anyone know if the screw holes in the Ruger barrel will have to be enlarged (drilled and tapped) to fit these Weaver bases? With the Weaver bases I can use standard rings and will not be subjected to the userous prices that Ruger charges for their rings. Thank you,
Gus

Semper Fi, If guns kill people, then pencils mis-spell words, cars make people drive drunk, and forks made Rosie O'Donnell fat.