Weaponeer.net has THE best 1919a4 kits you can find. Ask me how I know. LOL.
It is in some ways easier than an AK build. There is no pressing barrels, bending flats, concerns about matching #s kits for headspacing, or a need for expensive jigs. The rivets are easier to do (in my opinion...... probably not for most of you guys) but you will need to have some welding done. Hotbarrel is right about 1919a4.com. Those guys know their sh_t when it comes to 1919s and they are extremely helpful.
As far as the Izzy kits are concerned yes all of the affordable kits are Izzy. That doesn not mean that they weren't WWII USGI at some point. Some of them were and then converted to 7.62 NATO. Converting back to 30-06 is not difficult at all. I'm not sure why anyone would want to shoot more expensive ammo but you can if you would like to. You can even go as far as converting your 1919 to shoot dirt cheap 8mm if that's your thing.
Hope that helps. Don't hesitate to build one of these. They are not difficult and are a blast to build and shoot.