Hopefully it will come with a trapeze tailpiece. If everything lines up as well with the new kit as with this one, it should be great.

The measurement sounds about right. Gibson necks use a 24.75" scale length. That would be 628.65 mm, so your measurement is pretty close. If you want 628 on the high E, mark make sure that you glue the neck in so that the distance from where the string comes off the nut to the point where it comes off the saddle is at least 628mm. Even if this means doing a little work on the pickup cavity to make sure the neck pickup fits. Much easier to move the neck a little close to the bridge than to drill new holes for the bridge...especially if it is that close. In your dryfit, it certainly looks like the strings line up well with the neck, bridge and pickups.