I see it a bit different.
There are very few 1911's in production because a true 1911 is SA and in production all guns start DA and the few that are DA cant compete with the newer design guns that dominate that division.
Standard is dominated by 2011's which has some features in common with a 1911, but a 1911 is to a 2011, like a Ford model T is to a Ford model GT. Its got 4 wheels, doors, windows, seats, motor and trans, etc, but much newer technology and a lot more refined.
Antique division, oops, I mean classic division, is owned by 1911 because your not allowed to use anything else in that division, they had to put them in their own class, the original design and mag capacities limit them to competing amongst themselves. Although now that revolver can have 8 rounds I suppose they can combine those 2 division as there would be no advantage to running one over the other now...lol
To the OP if you are thinking of going with an open gun, you would be better served to just buy one of the "ready to go out of the box" models available from STI or Tanfogilo. They are proven, they run much better than most Frankenstein's and cause fewer headaches, parts are readily available, and in the long run will probably cost you less and be worth more if you ever decide to sell it.