[Ironangel]

A 427 is a 454 block with a 396 crank, or a 4" bore with a 3.76" stroke. What heads are on it now? Also, it would help to know what pistons were in it, domed, flat, or dished? And, do you plan on using the old pistons or buying new? Heres what I did when my L34 396 threw a rod out the side of the block. I bought a gen 1 454 truck block for $100 and bored it out .060" over to 4.310". Installed my 396 crank with the factory 454 rods and a set of brand new JE forged domes to fit the .060" over bores. That combo took the 396ci displacement .060" past 427ci to 439ci. Now keep in mind stroke is torque and rpm is horsepower. A shorter stroked big bore motor will deliver both if that rotating assembly is balanced to within a gram of fly weight. (gnats ass) And add a quality solid lifter cam and EDM lifters (EDM's is self oiling lifter, Electronic Discharge Machining with a hole laser cut in the face of the lifter) and you have an internally balanced Big Block Chevy motor that will spin up 8000 rpm and live to do it time and again! Now, your kinda stuck with that truck tall deck block. You got a couple of options, Mark IV engines saw extensive application in Chevrolet and GMC medium duty trucks, as well as in Blue Bird Corporation's All American and TC/2000 transit buses (the latter up until 1995, using a 427 with purpose-built carburetor). In addition to the 427, a 366 cu in (6.0 L) version was produced for the commercial market. Both the 366 and 427 commercial versions were built with a raised-deck, four-bolt main bearing cap cylinder to accommodate an extra oil control ring on the pistons. Unfortunately, the raised deck design complicated the use of the block in racing applications, as standard intake manifolds required spacers for proper fit. Distributors with adjustable collars that allowed adjustments to the length of the distributor shaft also had to be used with 366 and 427 truck blocks. You can either reach deep in your pockets and use that block but you'll pay dearly matching pistons and an intake to justify building the power it's capable of making. Or, set it back and find a cheap 454 block to throw that 427 crank in. That crank is most likely a forged steel crank and should also be an internally balanced version. You don't need that 4-bolt main block if you balance the rotating assembly, a must in any build! And you don't have the heads bought yet? Post some numbers off those heads you have, they may very well be some old school closed chamber heavy hitting heads like I had on my 396. That motor I'm building right now will have the 1969 3964290 heads with 101cc chambers. Them with 37cc domed pistons will end up at around 13.5:1 compression demanding 110 octane fuel. But that motor will live at 7500+ rpm beating up LS motors at the drag strip. Sometimes I wonder what it would do in a mud pit...