A Farmall cub had an advertised Hp of about 9 to 14 Hp, depending on the year.
IIRR they had a belly mount mower available of 60" usually made by Woods.
I don't see why a 72" mower driven by 18 Hp would not be viable.
Now admittedly, it would not be a "Brush hog" or a high speed, shake your fillings, zero turn.
