As for the BFS:

Mr. Stanley, and no doubt others, makes a perfectly good, large screwdriver with a SQUARE shank. These are commonly available at all big, green, blue, orange etc. hardware sheds and most smaller outlets, as well. Thus, you can close your 26" Gedore Shifter / "Swedishicon Key" on the actual turning bit and wind away, without marring the screwdriver with "tooth-marks" from a Stilson wrench.

If you have a spare stock bolt, you can use it as a pattern / gauge to adjust the tip of your new BFS to precisely match the slot in the head; Bonus points for "hollow-grinding" the tip.

Interesting bit of trivia:

The thread on the stock bolt (7/16" BSW) is about the ONLY thing carried over from the No1 series. No1 stock bolts have a long "wasp-waist" section that stays well clear of the wood, but has that wonderful square tip that has been the death of many SMLE fore-end in the paws of the unknowing. Someone at Enfield obviously discovered "spring washers" during the development of the No.4.

Final carpentry point: the socket (ferrule) is tapered, as should be the mating surfaces on the wooden butt. If the but just flops in, it MAY be repaied by some crafty wood-working. Also, the "shoulder" of the butt should NEVER touch the rear end of the ferrule. ALL the recoil thrust MUST be transferred via that inner face. If you have firm contact only at the shoulder, it will not be long before the recoil impulses ON TOP OF the stress from compression imparted by the stock bolt, WILL start to chip and crack the timber at the wrist of the butt.

I recall that Peter Laidlericon fully detailed the correct fitting procedures hereabouts.