You can do all the measurement and research you want, but in the end (no pun intended) there's no way to tell what saddle is going to work for you until you actually try out several options. Since you're DIYing the measurements, I can only assume that you're looking to purchase via Ebay or the like (since any authorized dealer will do all the fitting for you). If that's the case, buy two or three in the size range you think will work and try them all out. Keep the one that fits best and re-sell the others. Assuming you buy at a decent price, you won't be out anything on the ones you re-sell except shipping.