Finding a Chevy 427 big-block in the boneyard ought to be cause for celebration, right? Not when it’s a truck engine. These things are much more common than passenger car 427s. This one’s in a ’73 Chevy C60 5-ton tow truck. The hassle is that the truck 427 (and its 366-inch sibling) uses a block with a raised deck height (10.2-inch versus 9.8-inch for passenger-car blocks). The extra height wasn’t there for added displacement but rather to accommodate taller pistons with three compression rings instead of two. The extra ring and skirt length were intended to enhance cylinder sealing and add stability to the piston for reduced bore wear. While Pro Stock racers in the early ’70s sought these blocks for their ability to yield maximum displacement, they were never a big hit with the street and strip crowd. You can generally get better results with a garden-variety 454 buildup.