Well now, if we all wanted safety we wouldn't be hanging out here.
But, yes, I think this is do-able. If you run a 7/8" master, you will end up with appx 391 lbs of line pressure at 40 lbs from your foot. Then look for an aggressive brake bad. You'll have some brake dust, but she'll stop. If it is a tandem master cyl set up, try a 3/4" bore (front)and a 13/16" bore (rear)