I don't suppose there's a way to true a receiver at home without buying a bunch of equipment (square the face and threads). I don't have the $400+ bucks to be able to send it in for truing.
In my way of thinking I don't see that just squaring the face with the raceway without truing the threads is necessarily a good thing. Without know which direction the threads are canted I think you 'could' be making it worse by squaring the face? With remage actions, is there any knowledge to be gained by screwing the barrel in to the proper headspace and then screw the nut in till it almost touches the receiver face, and then use a feeler gauge to measure around the nut for variances? (assuming you have a quality machined nut)
All said, my plan is just to put it together and shoot it and see what happens. If it doesn't perform then I may consider having some truing done.
My plan was to put the remage barreled action into a KRG Bravo, thinking that that chassis shouldn't need bedded?
I confirmed with KRG that a .250" lug will work, and according to PTG their parallel lugs are the same height as a standard Remington lug. So a .250" parallel PTG lug should work.