We can build you a 427 with LS3 heads that will make the same power as the Mast LS7. It will be a dry sump though since that is the way we build them for durability reasons. I've been racing mine for 3 years and have never had any leak problems. We don't list any of our engine packages on our site but currently have a 600 hp, 650 hp package, and we are currently testing a 700+ hp package that will be going in my car shortly. Our horsepower numbers are with a mechanical water pump and accessories so they are real world as they would be in the car. PM me if you want more info.
http://www.kurturbanperformance.com/