Thre's no problem about the marks I referred to when using any A1 or A2 profile lower. The rail stops the open dust cover, and the worst thing that happens is that you get a small wear line on the center projection of the cover. Of course, you do have to close the dust cover on the early type, before closing the upper and lower. or you risk a mangled dust cover, but that's a different issue. (It's also the reason that the current type dust cover was created. GI armorers were tired of replacing mangled dust covers.)
No, it's only the flat side SP1s and 2s that have the problem that I referred to above. And i'm sorry, If you've had an SP1 for a number of years, and fired more than 2-300 rounds thru it, you are going to see, and hate, the damned outline on the lower. Mine has had that line for 25+years, and it gets worse and worse as the cover keeps smacking that flat side lower. At least w/the A2 type cover, mine won't get any worse than it is.