Hard to tell for sure from those pics what starter that is. Best bet would be to remove it to see if there are any markings on it (GM products should have part number stamped on it). You will also need to remove it in order to do a tooth-count on your flexplate....that's not as crazy as it sounds. Get the car up on jackstands, remove the plugs, stick a long-handle ratchet on your main pulley bolt and crank away. I used a piece of chalk to mark the teeth, and pen & paper to keep running tally of teeth counted. This is also a good way to verify that the teeth on your flexplate are all in good condition.
WRT starters, I've been using db Electrical for the last couple of years. They make a good product at a good price, and their customer service is unbeatable. I'm currently using a previous version of this little beauty; weighs only 7.5 lbs and features full support for the pinion gear at the nose:
http://www.dbelectrical.com/p-1319-new-chevy-305-350-454-mini-racing-pmgr-starter-ht-pm300-sdr0031.aspx
Good luck.
r/John