290HP Crate Motor Numbers

Where do they get 290HP from and what kind of fuel setup and exhaust are they using when they achieve this? Reason I ask is because I am thinking about buying a 290HP Crate 350 from Summit and would like to try and get 350HP out of it for my El Camino but want to know how they get 290HP and what I would have to do to achieve 350HP?
I am guessing swap the cam, headers, aftermarket intake manifold, 600cfm carb, etc? Will that even get me to 330HP? I would like to do this without changing heads of course.
I'd appreciate any information and suggestions on this. I do have a 355 in the garage now but I'd really like to stick that in my 63 Chevy II wagon since it will have a LT4 roller hot cam and Vortec heads, etc.

I would ask summit. I know sometimes they have upgraded optional parts. I would also check and see what you can do and not void the warrenty. if it's 290, probibly at the flywheel. could just buy a complete bottom end and one of the top end packages ie: heads cam etc. are you looking to go crate to have a warrenty?

and what is the difference in cost between you buying the motor, voiding the warranty upgrading yourself, or just buying a higher HP crate motor to begin with?

Red