Partzilla has OEM replacements in stock.

That said, and I can't believe I'm saying this, I actually would recommend a cheapo amazon lever. Specifically, an adjustable one. They have little levers (or rollers) on them that moves the resting place of the lever forward and back. This will definitely help you from having to stretch your fingers out so far. Check out ones like these or these. They're dead cheap, is a matching set left and right, and if you like it and want a quality piece, you can shell out for a nice Puig or something from revzilla later. Cheap amazon shit isn't always the best option but being comfortable and confident on your motorcycle is important so it's worth a shot.