Radial master cylinder pumps are designed to be in line, that is as you squeeze the brake the piston heads toward the handlebar. In the past they have been used almost exclusively by GP racers, but they have been available to the general public for at least a decade. The advantage is availability of larger bore pumps in a smaller size with a remote master. My friend with the Prince mounted the master in the corner of the HB muff.
Look at any Suzuki GSXR and it has a radial pump. Sizing aside, they are usually available on Ebay for little money. I am not pushing this, I just want you to have the info. No sense solving problems that you do not have.
David