Doug, I usually agree with you, and I do respect your experience. However in my experience of testing various real Cobras (a 260 in CSX2000, plus several 289 and 427s) I can attest that the 427s were quicker, unless (as you correctly point out) there was a vast difference in gearbox and rearend ratios.
While the BB Cobras do light up their tires through about 70 mph, the car’s weight is so low that it doesn’t sit there and go up in smoke like a heavier car with a lot of power. With practice, I was able to master the wheel-spin versus forward-progress skill to get the best times.
Yes, a full-race 289 would give a stock 427 fits, but I’m referring to both cars in street-stock trim. Every stock Cobra 427 I’ve tested ran between 12.8 and 13.4 sec. That’s at least a half-second quicker and than every stock SB Cobra I’ve tested.
One more thing to factor into the quickest cars list: A lot of muscle cars tested back then had one-legger (peg leg) rear ends, which obviously hurt times.
One example I’ve had time in, both in the day and more recently, is the ‘65 Malibu SS396 Z16, which was the first car to get the potent 396/375hp BB, 4-speed with 3.73 gears. My cousin had one new, and he gave me plenty of tire-smoking rides. I would’ve sworn it was quicker than any Mustang, GTO, Charger, etc. Until I track tested a fully restored real Z16 for Car Craft in the early 1990s. 100% correct engine and driveline specs. Even in the same color (Crocus Yellow with black vinyl top) as my cousin’s.
I was excited with anticipation. But, that excitement turned to disappointment on my first run. Everything was perfect on the car, it felt powerful and drove great, but couldn’t break out of the 15s. Run after run. 15.0s. Good mph in the high 90s, but what a disappointment otherwise.
A big part of the problem was that none of the Z16s came with Posi. Chevy had developed a Panhard rod rear suspension modification that was supposed to work as well as Posi to control wheel spin, but didn’t. Why they didn’t also include Posi is a mystery to me. With Posi (on stock type/ size bias ply tires) the car would’ve been in the low 14s with ease, and probably capable of high 13s with the best track conditions. Vintage tests of the Z16 showed very similar 15.0/97-99 mph runs.
But man, my cousin’s Z16 felt like it was the quickest car ever, back in the day…from a kid’s perspective. It sure could smoke that one rear tire for blocks!
BTW: The Z16 was the first muscle car to bring big bucks in price. In 1979-80, they were going for about what a BB Cobra was getting. They’re still over $200k for a property restored one. Only 201 built. 200 hardtops and 1 convertible. The convertible hasn’t ever surfaced and was probably ordered as a “brass hat” Chevrolet executive car.
There’s more that you’d ever want to know about a ‘65 Malibu, but is a great example of why most muscle cars weren’t as quick as we think they were.