Ensure that the 223 you are getting has a dimpled receiver and “mil” profile barrel. About half the guns have a different pattern barrel which is more work to properly make into a 100 series pattern. They’re amazing when they are converted though!
500m would be accurate. Don't forget the reinforcement plate. If you want to run AK mags you'll need a 5.45 bullet guide. The .223 ones for sale are for galil mags. Some modification has to be done to the front trunnion to get mags to seat. Not a gunsmith but that's what I have been told.
reinforcement plate goes sits above the pistol grip. Its a thin piece of metal. 5.45 bullet guide is what's used for 223 builds that want to use AK mags. If you want to use galil mags get the .223 bullet guide. When my 102 is built it'll have a 5.45 guide in it