Ian
When you get these bullets... look at the picture again you will see the top driving band of the bullet. Well you notice that these bullets do not look like your average bullet that has a cannelure or crimping groove. That is because with BPCR we do not crimp our bullets... I repeat we do not crimp our bullets. We use the sizer die and just run the case up into it, to just get a tapper crimp where the case is just snug enough to hold that bullet. If you use smokeless powder for your loads.... you almost can not get away from using a crimp because the bullet wants to fall into the case.
One thing your gonna need is a caliper to measure with. That top driving band will only get 0.010" above the top of the case mouth. Now in your case having your barrel reamed up, your going to need to get an empty 45-90 case with a dummy load of just a bullet seated to provide your gunsmith with. At least this is what I did for my gunsmith when I had my repro Sharps reamed up from 45-2.1" to 45-2.4" this way it allowed for the precise length that I wanted which was 45-2.513" and allows me to seat my bullets out to be 0.010" off the lands with grease groove bullets or even use my paper patch bullets.
Paper patch bullets are a whole nuther addiction :roll:
If you just tell your gunsmith to ream up to 45-2.4" you may not get the desired throating that your looking for.