Is this because of some injury to your ankle or leg? If so, it might be possible to have some sort of a ramp made up between the brake pedal and the footboard. This would mean your foot does not have to sit below the line of the pedal but would result in your foot always being at an angle which might not be comfortable.
A Friend of mine rides a Trike, he has no legs, anyway, He has a proportioning valve plumbed in the brake lines so he can use the front brake lever. He rides a 2006 MY motorcycle so I'm not sure what the valve would do to the ABS.
I agree with the pedal is not convertible. I have always had to replace mine on HD. This is how HD makes money. Anyways I have not found a pedal for the Indian yet. It would be nice to have it several degree lower. One company that does alot of HD pedals is Softbrake. I have been asking them to do Indian pedal but no results yet to be seen.