Never saw or heard of anyone using adapters. The 5 bolt pattern is large and so is the hub.
It would be hard to make the proper adapter.
A new axle will be much lighter and have the bolt pattern you desire.
Those 101A1 drums hubs and gear are heavy.
You can get back some cost by selling the wheels and axle on steelsoldiers.com
or craigslist. the wheels fit the older M57 and power wagons.