If you would like to use the repeatability of an indexed shifter, but are held back because the cable pull is wrong, you could try a Travel Agent. Travel Agents come in regular (designed to fit into the yoke on a V-brake) and in an in-line version. The in-line version is not currently in production, but are readily available, and are probably the best choice for your application. Here's an example (no relationship to the seller): http://www.ebay.com/itm/Problem-Solv...-/370606573179