Catpop,
When I did that, I didn't have any drawings. A friend of my Dad's had brought back a loaded round of 9mm from World War II, and loaned it to me for a pattern. I had that, and the barrel/chamber, and went to work with my drillpress and file. There was a lot of trial and error, but I was able to fire the pistol enough to enjoy it. The data was simply a wild guess, but it functioned the gun, didn't damage the brass, and I could hit the target, so I figured I did good. I didn't keep records back in those days, which was a mistake, so I have no idea what my data was, but probably used SR4756, since that's what I used the most of in .38 Special back then in my old model Blackhawk.
You should be able to make your 8mm Lebel revolver cases from .32-20 brass. For awhile, Fiocchi listed it as a regular item, but with the recent craziness, they may have dropped it. They announced at the SHOT Show in January of this year that their entire production for both their U.S. and Italian plants had already been sold for 2013, and were only taking orders for 2014, and that was just two weeks into the year.....
Hope this helps.
Fred