Sorry I believe you misunderstood. Should it be able to be 45-70, I would not shave the rim off of the ammo. But either thin the rim on the bolt face or shave it off entirely as to fit the larger rim of the 45-70. Both 30-40 and 45-70 are rimmed so just the extractor should just need to be tweeted slightly higher as to fit over the 45-70. I believe the  box can fit and feed 45-70 if enough space is created to fit the larger rim of the 45-70. Such as either creating a small deeper channel just for the rim. Or shaving it enough overall.