Matching olive drab knit to the cotton twill shell, and brown vintage mouton collar... By far the most common combination for B-10 jackets in WW2!
If you can get vintage brown mouton for the collars, that's would be best.
Talon zips are fine.
Personally, although alpaca is authentic, I don't think this matters so much. Rather use something soft and comfortable in the right grey colour.
WW2 Original B-10s with the 303rd Bomb Group.
Notice how the olive drab knit matches in colour to the olive green cotton twill shell, and the soft brown vintage mouton collars...