I have been thinking of buying a new marlin model 60. I have read they are having problems with canted dovetails. Does anyone know if this is only a problem when mounting a rail or does it cause a problem with standard scope rings?
Canted dovetail??? Don't know if it's the "dovetail" for the rear sight your talking about but I've had plenty of model 60s and never had a problem mounting a scope, either standard or the see-thru type.
If you're worried about potential problems if you bought a new M60, why not consider picking up a nice used one? There're about a gazillion of them out there in literally dozens of variations and levels of trim. It's quite often possible to get one in extremely good condition for $150 or less.
The one I own was my dad's, an el cheapo "West Point" model sold in Western Auto and some discount stores back in the day. It's about as reliable as gravity so long as you wipe the worst of the inevitable (in any blow-back .22 RF) powder residue and such off the works every 3-400 rds and don't overlube it. It's also amazingly accurate with its preferred ammo.
FWIW, Williams makes a nifty set of "Firesight" direct-replacement opens for the M60 that's very inexpensive and an easy, quick DIY job to install.