I have a 67 barracuda that by vin number should be the HP 273 four barrel. But when I got it, it has a 360 and the previous owner gave up on it because it had a "mean vibration that would shake the dash"
Upon my own inspection, after I got it home......I found that he had put the 360 in and used a neutral balance flywheel which is where I think the described vibration is coming from.