I have a M305, but it was accessorized at the time I bought it. It was topped with the original USGI Scope, which I had been looking for, for a long time. I think I paid somewhere around $1700.00 for the setup. I then mounted this scope on a Custom M14S with the M25 Receiver from LRB Arms. The M25 Receiver has the scope mounting slots forged integral to the rifle. No side mount, just like it was drilled and tapped for a normal scope.
http://www.lrbarms.com/m14receiversactions.html
While my M305 is not as accurate as my M14S which has outstanding accuracy, I found the accuracy could be improved by turning off the Gas Port, which effectively turns the semi-auto into a single shot Bolt Gun. When you are comparing groups, check this out.