Creating a suitably stout Corvette required an engine significantly more aggressive than the 283ci SBC that powered the '58 when new. McMahon went with an LS6 assembled by Aussie engine builder Thornleigh Cylinder Head Service. Thornleigh preserved the stock block and crank but slipped in Eagle forged-steel H-beam connecting rods and a set of forged Diamond pistons. Bolted to the block are AFR 205cc Mongoose heads with 66cc combustion chambers, Yella Terra Stealth rockers with a 1.7 ratio, and Comp 918 springs. An MTI B1 cam moves the valvetrain steadily with 221/221-degree duration, 0.558/0.558-inch lift, and a 114-degree LSA. The compression ratio is 10.5:1.
Ignition is sourced from an LS-series coil-near-plug system feeding ACCEL 10mm wires and A/C plugs. A custom cold-air induction system and a ported GM throttle body route air into a stock LS6 intake. Exhaust gases are evacuated through mild steel, ceramic-coated headers with 1.75-inch primaries, 2.5-inch polished stainless-steel pipes, and Hi-line stainless mufflers.
Back in the United States, Howell Engine Developments in Marine City, Michigan, reprogrammed the ECU to make the LS6 function properly in its new home. According to Howell's Troy Brown, "The most important piece of the puzzle was to make sure that the vehicle antitheft system was taken out. We then eliminated smog requirements, fuel-pressure sensors, rear O2 sensors, and any other nuisance codes within the computer. In addition, we reprogrammed the spark and fuel tables to accommodate the AFR heads and hotter cam installed in the motor."
Dyno testing by Stillwater Automotive Services in Silverwater, Australia, showed the '58 to be worth 395 rwhp, more than twice the output of the original 283. When McMahon feels the urge to unleash his Vette's potential, a Hurst shifter easily slams the six forward gears of a Tremec T56 manual that is custom-mounted to the chassis. "The T56 is a perfect addition to the drivetrain, and I love how the Hurst chrome shaft and white gearshift ball look just like the original '58 Corvette," he says. Allowing the Vette to make good use of all its newfound power are 17-inch PS Engineering wheels shod in Z-rated Daytona whitewalls.
The '58's cabin is worthy of accolades, too. McKenzie's Motor Trimming of Fairfield, Australia, recovered the original thrones in red leather and added a custom steering wheel, red-and-silver door panels, A/C, cruise control, satellite navigation, aircraft seatbelts, a Custom Autosound stereo unit (made to look like a factory unit, natch), a six-disc CD changer in the deck, and a Sony 4-inch rear speaker.
The toughest part of the interior was the gauge restoration, and for that task, McMahon again took on the challenge himself. "I made a new lens with kph rather than mph for the speedometer," he says. "Then I fitted an X-box that converts the speed pulse from the gearbox and drives a short mechanical cable that attaches to the back of the original speedo. For the tachometer, I used a VDO gauge in the original housing and the original fascia. I fitted a voltmeter inside the original amp gauge casing and made the front fascia appear like the original. The oil and temperature gauges are original."
Final assembly was performed by the owner, with electrical, brake, and engine details worked out by Andy's Restorations of Taren Point. According to McMahon, the results are "fair dinkum" incredible. At the Australia Summernats 2007, the '58 took on 1,200 competitors and received both Top Convertible and Top 20 Finisher honors.
But this is one Vette owner who has not found car shows to be his true calling. The real prize for him is the satisfaction he receives from having created a unique masterpiece combining vintage style with modern engineering. "The reason I built this Corvette was because I wanted the intellectual and engineering challenge it presented," McMahon says. "I thoroughly enjoyed solving complex issues on how to make the parts fit this car, and I ended up with a Corvette that is a trophy in itself. Owning the car is great, but building it was the best treasure."