Boosting an inline 6

[58chevyman]

I know this sounds a little different but i want to turbo my 235 chevy stovebolt. It is in a 58 chevy apache longbox sm420 with factory rearend. the motor was rebuild 3 or 4 years ago and was used in a hay sweep and is still a good running engine. I have heard that on a stock motor you can run under 8psi boost, so i have since acquired a turbo off of a 3406E Caterpillar and wonder if i can back the waistgate off to about 6psi and the motor still be able to hold.