The thing with tangs is that a lot of folks (me included) often don't get them bent as far as they need to be bent. Shortening the plug tab can help, but it doesn't fix everything. They're pretty springy when you're bending them cold. And they don't get fully seated until the tang bolt cranks them down. Or you have a space under there that puts stress on the barrel which can affect accuracy.
The way I dealt with getting the tang fully cranked down to establish the profile of the wrist and tang together (after inletting) was to;
1.) use clamps on the barrel and breech area to get it close so I could start leveling the tang and wood
2.) bend it a little more
3.) repeat steps 1 & 2 until satisfied
4.) drill and install tang bolt
5.) Use a flat-headed #8 tang bolt with an extra deep slot to crank it down to final position
6.) do the glass bedding of the tang
7.) file the tang and wood together to get to your final profile. The bolt head will get buggered up some, but this is a temporary and sacrificial bolt anyway. That's why you deepened the slot!
8.) rechamfer the tang bolt countersink as needed
Since you don't drill the tang bolt until the wrist profile is pretty much fully established (so you don't get it too far aft or forward and wind up with one edge of the bolt head proud to the tang) it is a problematic task to do just right. Guys that have done a zillion of them like Mike Brooks or Dave Person know how to deal with it and get the tang bends and inlets perfect, but I'm not that good. I resorted to glass bedding (epoxy putty or epoxy plastic wood will work too) under the tang once the bolt hole was drilled so the bolt wouldn't pull it down under the wood profile of the wrist. Then it was perfectly seated and no amount of pressure on the bolt could pull it down too far.
Also, you'll want to leave a small gap behind the tail of the tang, like .005"-.008" (about a playing card width). Partly this is to leave room for the varnish, but also to make sure the tang doesn't come back under recoil and start a split in the stock. That's less of an issue with a square-backed tang than one that's rounded or comes to a point, but it's still something to think about.