I’m an opinionated cuss so take this with a grain of salt:
You mentioned buy once, cry once, so what ever you do- don’t skimp on your scope mount or rings. My scope mount is steel, cause the action is steel, and shooting in a wide variety of temps, the similar metals expand and contract nearly the same amount meaning less stress on things and fewer fliers. The alloy UNITIZED rings are billed as being very accurately aligned meaning no kinks or marks or stresses on the alloy scope tube. Mounted to the rail, this allows just one more step in consistency. How consistent? Hmmm, multiple disassembly/cleaning/reassembly without zero shift (geeze, how many just cried BS!), yep, it’s true.
The rail has 40MOA because at the time I couldn’t find a 50. If I had to do it over, I might even go 60.
I own 2 Arken EP-5’s in Mil, and 3 Vortex SE’s in MOA. While I can use either, there is really no difference to me from turret standpoint, I prefer MOA for the reticle as the slightly closer indicators allow a more precise hold when I’m running holdovers and unders (90% of the time).
Lastly, the 40MOA rail allows me to dial down (iirc) around 35MOA, I consider that wasted vertical, but I can still reach out to over 500yds with standard velocity.
The Arken eye relief is WAY more critical than the Vortex, which can slow you down in improvised positions.
Lastly, if there’s a chance of shooting a night match, the SE’s Christmas Tree reticle lights up fully, with no dust specks or other annoyances, and you can run your reticle without worrying about seeing your turret settings or counting clicks.