Lee 58cal REALs are 440gr. Never seen a REAL in 525gr but trying to turn that rifle into a "sniper" with a cheap scope is a futile endeavor. Just trying to find a mount might be difficult. Is it even tapped well enough for a scope mount?
By the time you are done you could probably buy a new cheaper 50cal ML and shoot a 440gr-465gr conical. Used 54s pop up even cheaper.