Re: build no.2
If you want those drum brakes to operate like power brakes, do this simple mod. I did this on the go-kart brake on my ultralight and it made the brake work excellent.
Bolt a small ball bearing sliding patio door pully to the brake arm. run your brake cable around the pully about 180deg about anchor it securely to the frame. This doubles the cable tension when you apply the brakes.