I have scoped my NM for a number of years, especially since I don't use it for Service Rifle competition anymore.
A NM can be scoped the same as any of the other M-1A models with a receiver mount. I prefer & used either one of the Sadlak models or an ARMS #18 (old-style) mount. These mounts are considered the best & sturdiyist ones for the platform, although there are cheaper alternatives.
The issue about not removing the receiver from the bedded stock was mainly from the Service rifle competition perspective. This was more so with the Super Match model vs. the NM, and also if you had a wood stock vs. a synthetic one.
The issue was with a wood stock if you were shooting a few thousands rds a year that the wood stock would compress thus the bedding woulf loosen, requiring a re-bed. Stock compression is not a factor with a synthetic so this really not a problem.
I haven't had any issues with taking my receiver out of my NM but I don't take it out of the stock all the time.
So, IMO I'd pick out a top-notch mount and go for it. BTW - getting a good cheek-weld on a scoped M1A is an issue that can be helped with a add-on padded cheek rest.
I also use quick-release scope rings so one can take the scope off easier for storage, or use of the irons.
My .02