Reminds me that I'll have to take out my M-6 for a test drive soon.
As far as the original subject of this thread is concerned, I think that the Glass Reinforced Plastic top rail ought to be replaced with a good quality aluminum one, since any scope/ring assy mounted there will inevitably damage the soft plastic rail. The more often the scope is mounted/dismounted, the greater the wear. If the user plans to leave the scope/ring assy attached more-or-less permanently, then there is no issue with the GRP top rail.
Some low-profile, but rounded, rail covers might be useful for the remaining rails, particularly in the winter when using gloves
The action is simplicity itself, and it is possible a simple polishing of some surfaces, not necessarily the trigger engagement surfaces, might prove beneficial. Just a guess on this. I can think of other mods, but sometimes less said the better.
I see a front mounting point for a sling swivel underneath the front sight, but I don't see a rear mounting point for a sling. Perhaps this due to the supplied pix not showing such. However, if omitted entirely, this is a flaw, and should be corrected. FWIW, the SAI M-6 also omitted a rear sling mounting point, but since there was a screw near the toe of the butt-plate, a screw-in sling mounting stud can be easily added for a perfectly located sling attachment point. Perhaps a sling mounting point could be attached to the rail just to the rear of the trigger, albeit as some expense.
Clean the backside of the OEM front sight with alcohol, and paint it with NEON GREEN luminous paint, and you will be amazed at how much faster this, or any other rifle with black iron front sights, will be to use. Paint available at Brownell's and Midway. Do this mod to all your iron sights, be they rifle or pistol.
All this is just from looking at pix, without eyes-on view, or handling. Most of it common sense/experience talking. YMMV