Jayel is Right.
I used a drum from a '79 Honda XL500 and it's just as he says. Inadequete.
There are lots of good drum brakes wheels out there. Triumph is one. I just sold a 19" off a '72 for $75 in great shape. Should be a direct bolt on (5/8" axle). If not a custom axle can be made. Same with other Japanese manufacturers, they all had drums at one point.
Rick.