L76 has AFM, LS2 does not.
LS2 heads are similar to LS6 heads.
L76 heads are similar to L92 heads (better flowing).
L76/L92 intake flows better than the LS1/6 intake.
That's all I know at this point.
Why the less HP, not sure, perhaps a smaller cam and more restrictive exhuast?
This same L76 is rated 366hp/380tq in the full-size trucks.
Truck engines usually have smaller cams, so that kinda makes sense.
Then there's the L98 which is used in the Holden Commodore in Australia.
Same as the L76, except without AFM, and also rated 362hp.