[blykins]

A 347 with good heads will tax the strength of a factory block by itself. Add in forced induction and you have the recipe for a block split in half. Literally.

If you're serious in starting a project like this, I would get the advice of an engine builder, not a mechanic. Nobody runs .400" lift cams anymore. Modern camshafts are usually anywhere from .500-.600 lift on milder applications, then go up from there.

Do some research, and ask a ton of questions...

If it were me, I'd ditch the blower, and build a 450-460 hp 347 and call it a day. That's more than enough for a Cobra....one of my customers runs one of my 347's in a 7.50 1/8th mile class Fox Mustang and 500 hp in it will get him into the 6's (10's in the 1/4).