ee Enfields were made for a rimmed cartridge of similar dimensions and chamber pressure
The .303 British has a lower chamber pressure than the 54R. With sporting loads the variation is even greater, with the 54R nearing .30'06 or 8x57 pressure levels. I'm sure there's a way of doing it safely, but there's also room to screw it up.
I am looking for something that can produce at least MOA accuracy... The best I have heard of from the Mosin's was 2-4 MOA, and they vary greatly from one rifle to another
Many Finns will deliver MOA or better with the right load. The sights are fine tuned, and will enable an experienced shooter to engage any visible target within the cartridge's range. That includes targets out to 300, 400 meters and even beyond. This takes work and calibration. It may require you to relearn how to use iron sights, and how to use multiple points of reference to square up the target.
There seems to be a notion among those used to optics that unless you can precisely see the particular spot you're aiming at, you cannot hit it. If you learn how to use quality irons, you will be shocked at the tight and centered groups you can get EVEN THOUGH YOU CANNOT SEE THE HOLES or even the group until you walk up to the target or look at it through the range finder.
Particularly on the M28/30 and M39, the Finnish sights are really a sighting system of advanced design. This is the sight picture, and you will notice how the "dog ears" combine with the sight post, notch and the side posts to create a multi-layered sight picture with many points of reference to allow you to square up the sights with the target.
http://62x54r.net/MosinID/SightM39.jpg
With practice, you will be able to zero in while keeping the front sight in focus. Your brain will square up the rest of the sighting elements with the sighting points of the target--whether that's a circle, square or something else.
If you don't have time for all this or have no interest in it, the advice of getting a .30'06 Savage or Remchester is spot on.