Scrub brake setup
If you opt for scrub brakes, attached are some pics of the scrub brake setup on my cart. This is a home fab with a pillow block made from a piece of metal bar and pipe on the dead wheel side; the drive wheel side has a piece of metal pipe welded to the leading edge of the engine plate.
The other piece you need will be a 4 inch piece of metal bar welded perpendicular to the torsion bar, pointing down. This is where the brake control rod attaches to the torsion bar to actuate the brake paddles against the tires.
I believe this cart was originally a friction band setup since it has the bracket and pin on the drive wheel side - you would need to fabricate something similar if you go for a friction band setup.