I ended up buying a lighter vest and a heavy fleece vest. Got them a size smaller so they would not hang below the jacket. Have used this setup for the last several Winters.
Now, if the temps drop below 10 degrees (F), I switch out to a work style heavy lined canvas jacket.......
I have found with HH and cowhide with the vest, you will stay pretty warm if you are moving. I used to walk to work when in Germany and would actually sweat through my shirt. This was in the Winter when it was pretty cold.
I have read that unlined leather jackets are just an insulator from wind and the elements. It is what you layer underneath that determines how warm you stay. I would think the Wested standard lamb and any of their jackets except for the really light ones would be alright.
I think the weight of the HH makes it a colder weather jacket. Has to be in the mid-forties or below for me to wear them.