Buick roared into the 1970 model year with the baddest weapon in the GM armory, the Gran Sport Stage 1. The formula had been percolating within Buick’s engineering department since 1965, when the division answered rival Pontiac’s GTO by making the Wildcat’s 400/325 HP big-block V-8 available in the GS along with the usual muscle car accouterments—a 4-speed, bucket seats and heavy-duty suspension and brakes. Styling, however, was generally seen as uninspiring, and Buick’s entry into the performance sweepstakes went relatively unnoticed despite its power and relatively luxurious interior appointments. Then, in 1969, Buick hit the right note, rolling out the Stage 1 GS 400 rated at 345 HP and 440 lb-ft of torque, followed in 1970 by a new 455 CI big-block churning out 360 HP and 510 lb-ft at just 2,800 RPM, sharing the highest torque rating ever in any passenger car with the big Cadillacs. Those same numbers can be found in this two-owner 1970 Buick GS Convertible, which retains its matching-numbers 455 CI engine mated to a 400 Turbo Hydra-Matic 3-speed automatic transmission and 10-bolt 3.42:1 Positraction rear end. Its second owner of 32 years, a professional mechanical engineer, personally rebuilt and upgraded the standard-bore GS engine to Stage 1 specifications, following the factory blueprint for the ultimate Buick muscle machine as part of a body-on restoration that included new Fire Red paint and a new black soft top to match the mostly original and well-kept black bench-seat interior. Beautiful, powerful and luxurious, this 1970 GS convertible was sold new by Jim Kelley Buick in Fort Wayne, Indiana (Dealer Zone 491 in Zone 07), and offers power steering, a power top, bright wheel arch and door edge moldings, headrests, a Sonomatic radio, tinted glass and 5-spoke, factory, chromed wheels wearing Firestone Super Sport redline tires. Documented with the Protect-O-Plate, line number build sheet, owner’s manual, sales brochure and maintenance receipts, it retains most all factory-correct- type components including the spare, front and rear floor mats, trunk mat, seat belts, washer system, soft top boot, carburetor, air cleaner, hoses, hose clamps, fresh air hood, warranty book and T-3 headlights.