In the SKS rifle for J bullet in 123 to 150 gr. range I like AA-1680,Reloader #7 and H-4198. The AA powder are no longer sold in my area but it was a excellent powder when I used it.
I have use Reloader #7 pretty much exclusively for the past 5 or so years with excellent results in the above bullet weighs,it also can be used with either of the Lee 155 to 160 gr. gas check cast bullet loads and 18.0 grs. of RL#7 will cycle any SKS rifle that I've tried it in. H or IMR-4198 are good powders as well. The above powders I mentioned give the best bang for the buck as far as charge weight and have given me excellent accuracy.
If you shooting cast loads using either of the Lee X39 gas check bullets in the SKS my personal preference is Alliant 2400 using the Lee TL 160 gr. GC bullet. You can start at 11.0 grs. and increase the charge weight by one half grain until you get reliable cycling up to a Max. load of 15.0 grs. My Chinese SKS will cycle all day long with 12.5 grs. 2400 and drop the brass right at my feet MV @ 1450 fps. I also shoot a Max. load of 14.5 grs. 2400 in both my SKS rifle MV @ 1950+ fps.
H-335 will work in the X39 cartridge as well but the starting load is about 3 to 4 grs. higher than the Max, load of the above mentioned powders for J bullets so you get less loads per lb. use it if you got it,it works.