Okay, so the markings aren't 'all original'. They were original enough for the Army, and that's who she was built for. All the changes do is show you some of the rifle's history. If folks can complain about that, then I have several Lee-Enfields which have been 'ruined' or otherwise 'defaced' with D/!\D and C-Broad-Arrow stamps, even one completely wrecked by an unsightly N/!\Z stamp.
That stated, it is a lovely rifle and it should turn out to be a good shooter.
FYI, I find that your best shooting will be with a 180 flatbased bullet, followed by a 150, again flat-based; the rifling in Lee-Enfields really doesn't love boat-tails all that much but it is superb with flatbases. If you are handloading (shoot for half-price..... or shoot twice as much for no more money), go for a handload with the 180 that will give you 2250 ft/sec by the book. This is, by test, the most accurate velocity for the .303. I have several that shoot brilliantly at this velocity, but groups open up with faster loads. Seat to overall length of a Mark VII Ball round.
Lee-Enfields are the slickest actions ever made.
Most important of all: enjoy your toy.
It WILL have company before long!