A friend has a 28 ga repro with beavertail.
THE WOOD HAD A CRACK OF A 1/16 INCH NEAR THE RECIEVER. HE SENT THE
forend back and they replaced it and sent the old wood back..I got it and it mounted perfectly all screwed holes matched on a splinter iron. Of course there is a blank hole where the bolt is supposed to go, but as far as fuction, it works fine. I wI'll post pictures tomorrow as the gun is not nearby. I have shot 2000 28 ga shells st skeet and with the .410 Barrels , probably another 1000 shells.
The beavertail holding firm to splinter iron.

OK, the 28 ga. Repro BTFE iron measures 5 10/32" overall length and the 28 ga. Repro splinter iron measures 4 28/32" so, they can't be swapped without some modifications to the wood. Both irons seem to have the same taper in thickness but, of course, the BTFE becomes thicker due to the fact that beyond the recess for the forend loop it needs to be thicker to allow for the threaded hole to receive the reinforcing rod.

You can put the short iron in the long
beavertail wood with no problem as I said to put splinter wood on the beavertail iron would mean cutting out about 1/2 inch of wood or maybe more