I think your on the right track in looking at the bedding. Sorry to say but there is a lot more bad bedding jobs than good. Removing the material supporting the first couple of inches of barrel I would do first. Also make sure your screw holes are a bit larger than the action screws. A rat tail file or chain saw file is perfect for this.
I’ve seen where M70’s have preferred a single contact point for recoil. In other words, they didn’t like the area under the tang acting as a mini-recoil lug. If you bedded this area, I would remove some material that would normally absorb the backward thrust as the sides of the stock where the mag well is will flex under recoil.
If that doesn’t fix, remove a very thin layer of material under the lug. I’ve seen some not care about this, while others preferred that the only bottom contact point be the flat surface behind the lug. Keep tinkering you will figure it out and learn a lot in the process.
