IMO, either set it aside for the day you might stumble across a good used larger size (1") Hawken stock in which case you can drop it in and use it...or resell it.
The difference between the two different size Hawken stocks (regular for the smaller, lighter, less recoiling .45/.50cal x 15/16" barrels) and the larger size Hawken with the full 1" wide barrel channel for the larger, heavier, more recoiling .54/.58cal 1" barrels.
I've tried to list what I believe are a number of reasons why cutting up the smaller / regular size Hawken stock to try and fit a 1" barrel is not a good idea:
1) With the one inch barrel being too large for the existing barrel bed, the whole bed would have to be enlarged by shaving down all the flats...sides and bottom;
2) Then this will put the wedge pin tenon too low and the ramrod won't slide under it so the tenon will have to be filed thinner so it won't extend down so far;
3) The brass nose cap flats would have to be reworked wider to accept the 1" barrel;
4) The 15/16" tang would have to be removed, and inletting done to allow a 1" tang to fit down into it's space so it sits behind the breech and mates properly with a 1" breechplug;
5) Then, the wider barrel would physically push a Flintlock assembly out of it's mortise some...or if a caplock, it would have to be shimmed out of it's mortise some to get the hammer to line up with the nipple sitting further outboard on the wider barrel;
6) And after modifying all that the resultant stock would be even weaker than it originally was...just the opposite of what is needed, of why a larger beefier stock is used for the larger more powerful .54 & 58 calibers.
Just my .02 cents on the matter...
