It's been over thirty years, since I converted a 700ADL I had to the BDL mag config - but IIRC, I just ordered the correct length BDL bottom metal assembly (trigger guard, floorplate, latch) from Remington.
I then cutout the wood of the blind mag part of the stock, and inletted for the new bottom metal, and used the old sheet metal magazine box, follower, and spring.