These engines are truly impressive olddog (apologies I know your first name but I'm having a senior moment
). Don't get misled however by doubling manifold pressures and expecting to see double the torque and power. When you double the manifold pressure you need to use a compressor.
If it is a positive displacement belt driven unit like a KB or a Whipple then you will consume power to drive the compressor and that power will not show up at the flywheel. A good rule of thumb is somewhere between 125 and 150 HP depending on how much boost and how efficient a compressor.
The net net bottom line is the engine will probably see a best case scenario looking like somewhere between 600 to 650 ft/lbs of torque and somewhere between 750 to 800 FWHP at 6500 rpm — ask me how I know
Two of the very intoxicating aspects of the PD blown versions of the engines are the impressively flat torque curve they have from essentially off idle all the way up the rpm scale and how far up that rpm scale you can go. Of course increased engine speeds beyond 6500 will bring correspondingly higher power numbers. Using reasonable cams, properly phased, the 4V pent roof design heads have a stunning air flow capability across an extremely wide engine operating rpm range.
Here are two different cammed examples of a supercharged version of the engine idling. While healthy sounding, our traditional Cobra idle is not evident. To produce the traditional sounding big block Cobra idle you would have to narrow the LSA between the exhaust and intake cams.
First Car Idling
Second Car Idling
The second car more closely approximates the Classic sound but still is not period correct. Again the LSA between the intakes and the exhaust needs to be narrowed up a bit.
Ed