Nordi,
I personally have 40K mi on my 347 and it still runs strong. Getting 475fwhp with an Xcam is very wishful thinking. You definitely need a custom.
BigZach,
HiTech Motorsports in Houston had a 347 that put 455 to the tire with some fairly streetable parts. This was a while ago so there might be 347s out there that throw down more. Realistically if it's done right you should be able to get 380-400rwhp or so without much hassle.
I personally have 40K mi on my 347 and it still runs strong. Getting 475fwhp with an Xcam is very wishful thinking. You definitely need a custom.
BigZach,
HiTech Motorsports in Houston had a 347 that put 455 to the tire with some fairly streetable parts. This was a while ago so there might be 347s out there that throw down more. Realistically if it's done right you should be able to get 380-400rwhp or so without much hassle.