I've said it before and I'll say it again. Rego/compliance/etc aside, my ultimate Cobra would be a 289FIA with a 13.5:1 compression short stroke, small journal small block with all of the lightweight billet and titanium and beryllium internals that money could buy. Throw in some monster high port 400cfm @ .800" heads and a ridiculous solid roller camshaft with valve spring pressures that would make a weightlifter wince. Top it all off with a crank driven dry sump pump, a 7.25" clutch and Spook's Holinger sequential. With it's barely muffled side exiting pipes, alloy panelled interior, a tach that shows a choppy 1200rpm idle, an unusable rpm range under 3000rpm and a redline of 9500rpm, the picture is complete.
OK, I've just come back from a cold shower. For those who haven't seen the differences between a 289FIA and a 427 body style...
289FIA vs 427