Basically just a Boss 302 with more cubes, the solid-lifter Boss 351 was a one-year wonder that hit hard on the tail end of the muscle car era. It was also one of the stoutest street Mustangs up to that point.
Read the full article at Hagerty.com: https://www.hagerty.com/media/magazine-featyres/25-greatest-mustangs-1971-boss-351
I’ve owned all 3 bosses. Mechanically the BOSS 351 was the ultimate. Boss 302 lacked torque and the Boss Niner was a real unreliable (slower than a 428CJ) nightmare....even when it was brand new, I couldn’t find a Ford dealer to do decent warranty work on that car. We finally found many of its defects (like the BuddyBar intake had pinholes in the bottom of the intake! Also the valve springs were super weak... and many other issues)
But, it did handle well... better than the 2 Boss 302’s I’ve owned.
I feel a 1970 Boss 351 would have made real history! Hindsight is 20-20.
I've had my '71 351 Cleveland for 43 years, and she still brings me a thrill. I'm lucky to be alive after the way I drove her in my teens. She's a 2bbl, not BOSS, but I wouldn't trade her!