One excellent choice of a replacement engine for your original is a Chevrolet crate engine from GM Performance Parts (www.gmperformanceparts.com). This is the ZZ383 crate engine shown as it comes, whereas the ZZ4 comes a little more complete with an aluminum intake manifold and H.E.I. distributor or as a "turnkey" engine ready to run. They both come with a warranty.
Beneath the skin of the 383 is where the real beauty is-with a full-roller valvetrain, nearly bulletproof balanced lower end and high-tech aluminum Vortec heads with taller intake ports and a swirl-inducing design built to make horsepower and torque-425 hp and 449 lb-ft of torque-on pump gas. The stock hydraulic roller cam needs no upgrading, and has a nasty get-outta-my-way personality to it. The full-roller rockers are strong, lightweight, and designed to rev freely.
Look at the big picture before starting a project like this. For instance, this '67 is getting this powerhouse GMPP ZZ383 small-block and a Classic Motorsports Group Tremec TKO 600 overdrive transmission with a .64 Fifth gear. This engine/transmission combo is a great match because the engine makes big torque numbers at low rpm, which is where this engine will reside while in Fifth gear on the highway. It's important to match the power curve of the engine with gear ratios in the transmission as well as the final drive in the rearend, and all of this according to the type of driving you'll be doing, along with accessories you will need to run, such as power brakes and A/C. Knowing what transmission you'll be running makes installation a lot easier by installing the two as an assembly.
Planning starts early on a full restoration with questions such as: where are you going with it? how do you want it to look? what are your performance expectations? This '65 is a full rotisserie restoration with the original transmission and rearend, but with a ZZ4 crate engine up front. We've installed crate engines to preserve the original engine, or where there wasn't an original engine in the first place.
It's a marriage of disciplines-the NCRS-type restoration on the better part of the car, but updates and upgrades blended in either on the surface or in a stealth way beneath the skin. My philosophy is to burn no bridges in the restoration process-allow the car to be put back to stock should the need arise. Someone down the road may want it back the way it was, and it just makes good sense to leave that option open. In the meantime, enjoy your car your way. You would be amazed at the number of enhancements available that will simply bolt on.
The WOW factor under the hood of this '65 is unbelievable. This is the ZZ4 with glitz to the Ritz, and 355 hp on pump gas. We've upgraded the hydraulic roller cam so it has more attitude and speaks of presence with headers and under-car chambered exhaust.