YMMV, but most recent LH1431 flights have parked on the apron and passengers were bussed to the terminal.

Once inside the terminal, head towards A15 where you go down to the tunnel that will take you to B.

When you surface from the tunnel, exit passport control is on your right.

That puts you in B non-Schengen and you head to your gate.

Usually doable in 80 minutes. Delays on your inbound are your biggest risk. If it's snowing that'll likely be a wash as everything will be delayed.