Just got handed a 800B for free that I spent Sunday (snowing so nothing else to do) going threw to clean up and covert it over to a C.
Again, the secret to trimming the sizers is back up the cut end of the sizer with a live end in the tail stock.
So bottom of sizer in the chuck, live end on the other side, set the Carbide cutter to the angle you want the angle on the shoulder, and make your cut just short of all the way through that will leave the end of the sizer with a ridge bur, and about .010 longer then needed to that end of taper end of cut. Since you have the lathe already set up to just make plunge cuts on the cross slide, you just go through the dies this first step to make the side taper cuts for the set of sizers.
Now on the second pass of the sizers threw the lathe, kick the cutter to about an 20* inward angle, set the cross slide .040" to the right, and then feed the cross slide to tip inside the sizer, set the cross slide to 0 inside the sizer and make that last facing cut outward from the inside of the sizer to the outside of the sizer (live end not needed for this cut, but use it as you are tightening the chuck to make sure that the sizer square and tight against the face of the check for repeats ).
From here while you still have that sizer in the lathe spinning, cover the cross bed with a towel, break out a file for the ID edge to break any burs there, hit the end face to start of side angle to soften that edge, as well as the end angle to flat of sizer OD with the file. Now with some 400 wet dry sand paper, go back and gleam the edges, and add in that touch of chamfer to the ID of size.
Note, don't go buck wild with the file, but since you will using sand paper on your finger to do final polishing and the light ID chamber, make dam sure you don't leave a sharp bur to cut you when you go in with the sand paper after the file.
Next, kick the cross slide back over to the right .040, pull the Sizer, use the live end/tail stock to tighten the next sizer in the lathe, and off you go again for the next sizer final step.
Hence done this way and you have the first sizer cut to plus .010" plus bur and the Z axis on the cross slide lock in place, it only takes about 4 mins to trim a full set of sizers since you just doing repeat cuts on each steps .
As for carbide cutters ( I just use T-321's), C5 will do the cuts, but you will wear out a tip on a set of sizers. C6 tip will last you around three sets of sizers. C-7 cutter tip will do boxes of sizers before you need to spin the dulled tip instead. If you want to go faster on the cuts, then ceramic cutter is the ticket, but your dealing with glowing red hot ribbon chips coming off the cutter (all all the smoke when they hit the flood oil) instead.
Also, let the cutter do the cuts, instead of putting a ton of pressure on the tip instead. The swarf you want will be fine grind type swarf off the cutter, and not trying to get ribbon chips off the sizers . Also, since the first pass is going to be a thicker cut, make sure to back up the sizer with the live end for this cut. You start to get any chatter, and you can kiss the tip good-by on the carbide cutter.