Help Identify what BM fits in an older Proof Tac II Stock

[CA48]

Trying to find LA BM for this so the Smith can finish my 30 Sherman Mag build. This was off an older full proof rifle in 338 Lapua BDL originally with a Defiance receiver (same screw spacing as Rem 700) I wanted to run a DBM set up but at this point I would be fine with a BDL. Smith says it's not an M5 or Oberndorf, not anything he's ever worked with. He spoke with the guys at Proof and they didn't recognize it either. Any input on what you think this might be would be greatly appreciated.

7 3/8" action screw spacing
Box inlet is 1 3/16" at the front
1 1/4" at the rear.

 

[patrol120]

Seems like older CDI metal was shaped like that, but I haven't seen any in quite a while.

 

[CA48]

Thanks for the help but the smith just used Hawkins M5 BM and filled the gaps with devcon.