Yeah I hear you on the HP war with your brother. You should be able to put a nail in his HP coffin with a nice crate motor for sure. Heck for that matter a nice 6.4 would do the job. 525 HP right out of the box. Mate that with a tremac 6-speed and "you da man". LOL. I'll be looking soon for a big block for the X so let me know what you find. Are you running a DANA or 8 3/4? Either is great and can take the abuse of a 600 plus power plant. The Dana will hold much more.