Ditto on 1919a4.com, thats the place for all good 1919 info. Linking by hand is not hard, but time consuming. If my buddies want to shoot we have a linking party and everybody gets to enjoy a half an hour of linking.
As far as building your own, I don't have access to machine tools. Buying a kit for 300-400 dollars, spending a couple of hundred on machined semi-parts and a side plate, riveting and parking and hours of work add up to pretty close to the price of a decent 1919. I got mine early on from Ohio Rapid Fire, it was a test build gun. It has ulgy rivets, side plate marking looks like hell and it had a bent rear sight. BUT, with a little tweaking on all of the minor parts it is a blast to shoot.
Gun weighs 25-27 pounds, tripod another 20 or so pounds. Watch for specials on 1919a4,,every now and then they do a group sale or purchase of guns. NEVER buy anything from Hesse or Vulcan and you should do ok.