The 6.0L iron block found in trucks and Escalades is the common block to use for the popular 400+ cubic inch stroker LS-based engines, and is a fairly strong piece. Also, the newer Escalade 6.0L engines have the very impressive L92 cylinder heads, which are essentially a LS-7 head with a larger combustion chamber. These heads will go 330 cfm on the intake runner at the .600"-.700" lift range straight from the factory. The power potential for these heads is HUGE. Also, the earlier Escalade engines are no slouch, either. The heads on those engines are basically an LS-6 head, again with a larger combustion chamber. It's really pretty hard to go wrong with any of the LS-based engines for a build-up. Even the 5.3 can be turned into an extremely stout performer, especially with a power adder.