Valeriaa Brown

I have a stock 6.2 around 41,000 miles. Looking to make close to 600 horses as possible w/out nitrous, with daily drivability although it want be driven daily. Im trying to figure out would it be better for me to sell the 6.2 and build the 408 or to use bolt ons on the 6.2 to achieve this using the least amount of money need help asap thanks