Planning HD Upgrade

Currently have 3 sd receivers running from multiswitch and two rg6 coax running to dish. Dish is a 30 inch round dish mounted on steel post. I want to upgrade one receiver to hd and keep two sd receivers. The coax run from dish to multiswitch is 100 ft and run from multiswitch to each receiver is 50 ft for each. Does anyone know if I can get DirecTV to upgrade the one receiver to HD, replace my Dish with 5LNB Dish, keep the two sd receivers use some of my current RG6 already installed and any idea of cost?