[mountn man]

There'd be something about a big block bumping and thumping under the hood. Displacement might be the same, but the big blocks sound so nasty.

That said, todays boss blocks, at 427 ci are hard to beat. Inexpensive to build vs the FE's.

Order one up from Ford at $10k and you have 535hp, $15k =600hp.
A Robert Pond 427FE at 600hp=$20k

500hp in a SB 427 in a Cobra, would be sick. The originals had 425 horsepower in 2300-2400lbs, don't know what the Factory Fives weigh, but if the chassis weighed the same, you'd have 75 more hp with 100-125 lbs less weight. You'd go from about 5.5 lbs per hp to 4.4 lbs per hp.

[nascarnation]

His car is almost identical to this one, even the color:
http://www.hotrod.com/projectbuild/hdrp_0512_cobra_crate_test/