I recall there were some transfer cases that had the park brake on them, very much like what you have now.
The other option would be to find in wheel park brake parts for your existing axle which probably exists. Or maybe even find a different donor axle with park brakes.
Those are the stock parts solutions. If the 271 is a fixed yoke version it would probably be easiest to adapt a small rotor to the output flange and build a bracket to hold a cable actuated caliper. This is sometimes done in the off-road world. Just say this as an option for the Atlas transfer case this year at SEMA. But if you have a slip yoke version of the 271, not going to work.