I just built forward controls for CB 500/4. Method of linking brake to brake lever has worked really well and looks very neat.
I used a heavy clutch cable with adjuster from a Harley (Shovel is probably the best). I welded a threaded (5/16 UNC) mounting point on the brake arm (goes from brake plate to frame) to receive the adjuster.
I drilled and threaded (1/4" ) one side of the small cylindrical steel block that normally takes the brake rod at the brake lever. The opposite side I drilled (up to brake rod hole) to 3/8".
Then I inserted cable through what was the brake rod hole and tightened up a 1/4" bolt against the cable. Cable can't slip because bolt forces it to partially bend into 3/8 hole.
This is the brake pedal mounting. Stock brake light switch is held to cable with 2 cable ties. Original spring clips into small hole in brake pedal ...
Also for gear lever extension... If you don't want to spend big money on rod ends, make clevis's out of 1/2" bar with an angle grinder. For the pins, use some 1/4' rod (or cut up a 1/4' bolt) and pene one end over and drill the other for a small split pin. Saves money and you did it yourself and no one else will have one the same.
Hey man, shed built bikes are best!