We share the same 243 heads(ls6).I don't know a lot about the LS variants but I do know a 5.3l has a smaller bore than the ZO6 engines so I find it highly unlikely you have the same head casting. I would be deeply suspicions of the quality of any other "information" you get from the same source.
At the engine, probably. But why do you care what you make at the crank?400 at the engine should be doable. If I read correctly we have the same heads as the z06 just different valves. A cam, tune, and exhaust from the headers back should do this right. I dont care for the dod so it can go.
Been so long since the Vette got the 5.7l I forgot about it.We share the same 243 heads(ls6).