Tim; the best thing to do in a situation such as yours is to stick with the same brand of components all the way. This is because this is what is generally what is used by the testers who develop the data.
So, my first choice would be a Winchester powder, especially since there is a wonderful powder, 748, that seems to work well in this cartridge capacity range. So, go to Shooter's Gunlinks, at:
http://www.shooters.com/gunlinks/index.htm
click on 'product manufacturers-non firearm,' and download the Winchester Reloading Manual. Check under 7.62 x 39. DAMN! Nothing there.
Now, comes in the crafty part. Being an oldtimer, I happen to know that most Hodgdon powders are manufactured by Olin (Winchester). So go to Hodgdon, and download their manual at this website:
http://www.hodgdon.com/ check the rifle data, and WOW! There it is; a bunch of data, which utilize powders such as H-335 and BL-C2, not coincidintally very near the burning rate of Win 748!
I would start with these data, but would do the following two things first: check with Hodgdon and find out what type of cases and primers they used to develop their data. Second, check with Olin/Win to find out if they have any new data regarding this cartridge.
This is a good way to research any caliber. Go to the shooters' gunlinks website and find out what data exist for a given caliber. Match as closely as possible all the components used to develop these data. Compare other sources of data to make sure that they are all in the same ballpark (if you find a load 3 or 4 gr. higher than anyone else recommends, don't use it).
Remember that data more than a few years old probably used the old copper crusher method, which has been replaced with the much more accurate piezoelectric method. Re-evaluation of existing data by this new method has, in several cases, resulted in dramaticly reduced recommended loads. So, do it the new way; use the internet. Don't bother with reloading manuals unless you absolutely have to (by which I mean the traditional printed ones).
Be careful, and be safe. Walt Welch