It appears your receiver was set up for a detachable style magazine, as there are no feed lips to facilitate the cartridge retention when you load from the ejection port in the ADL/BDL format. I was Nesika's production manager from 2003-2006, and I own all of the remaining product inventory. (Remington killed the brand around 5 or 6 years ago, and I bought everything from them right before the bankruptcy implosion)
The question now becomes, is there enough material remaining to convert it to an internal box magazine?
Looking at your pictures, I'm going to speculate the answer is no. One way to check is to slide a cartridge through the opening. If it has a mile of room on each side of the cartridge body near the bolt circle, then insufficient material will likely remain to create necessary feed lip features. Keep in mind, I'm guessing as I am only judging this from photos. It's just as likely that I'm wrong, and all this requires is a box mortise to be cut into the receiver body. These are dimensions that I "should" know, but understand that I left the company almost 18 years ago, and things continued to evolve.
The next part of this concerns the loading/ejection port. Many detachable magazine-fed Nesika actions used a target style ejection port. If I recall, a "V" action has a hunter/open type, but the "thing" about Nesika was that you could configure the action into just about anything. If your receiver has the open/hunter-style port, it's a good thing. You'll be able effectively to load/clear the action when in use. Target ports and internal box magazine setups are not user-friendly.
Happy to help
C.