Look at these pages:
http://www.summitracing.com/parts/edl-28215
http://www.summitracing.com/parts/hly-112-577/overview/
http://www.summitracing.com/parts/hly-550-602
These are just an example. You have the EFI intake, throttle body, and ECU. You could also use a FAST ecu computer system which would probably be easier to adapt to the throttle body.
You can also go this route which uses a traditional intake manifold and a throttle body with injectors in the throttle body.
http://www.summitracing.com/parts/fs...-kit/overview/
In both the Holley HP and FAST systems, they make kits specifically for a LS engine, so they are relatively easy to install if you know what you are doing.