Whether the wood inserts are to reinforce the new drawers or to prevent the rear of the fore-end moving from L to R, I can't really imagine an Enforcer being repaired in such a way. Simply based on the fact that in the great scheme of things, they were used very little, didn't get a hard life and were very probably a one-man-dog so to speak.
As a bit of an aside while admitting to being a bit of an amateur here, I can't really see the point of the two wood peg inserts to prevent the fore-end moving or tightening anything. After all, if you really needed to tighten it up a tad, you'd just screw the tie-bolt/nut up a bit. That way the rear of the fore-end would grip the Mk1/2, 1/3 or 2 trigger block. End of problem. That's how we did it when fitting fore-ends in the first place