These engines are rated at 362hp unmodified, due to their slightly lower compression ratio of 10.4:1 instead of 10.9:1 and the tamer camshaft. Lower compression cause the chamber is slightly bigger. These heads need at least 4.00 inch of bore and therefor can't be used on LS1's.
However they offer far better potential than the regular LS2's since the L92 heads and the L76 intake manifold flow so much better than the cathedral port versions. A mild camshaft, headers, cold air and a proper tune puts these engines easily into the 520+hp range. For flowcharts and performance figures have a look at:
http://www.gmhightechperformance.com...ads/index.html
Lots of info about (tuning) these engines can also be found on
http://www.ls1.com.au/ where these engines are known as the L98.