Why not rig a 90 degree elbow to the stock intake, and mount the TBI vertical instead of upside down? Of course, you'll need the full complement of sensors and an ECM to match the throttle body, wire harness, etc. but that can all be scavenged from a suitable donor vehicle. Since you'll be making an adapter any way you go, try a 2-injector TBI from a GM 3.8L V6. It should flow plenty of air volume without having to deal with the hassle of synchronizing two single-barrel TBI units.
Jerry
