what des it take to stroke a 360 to 408?

sorry i knew i was forgetting info. I have 2.02 1.60 cast heads. they are ported and polished and bench flow tested, Im running a 3.23 SG in my 8.75, i just purchased a set of used headman headers of this forum, i plan on going to 3.91's as soon as i sell mine and find some, im also running a stock 340 high stall. This car was originally a 273 car so someone before me had dual 2" with an h pipe put in. I am running 2.5" flowmaster super 40's with no tail pipes (Im getting lots of exaust inside the car). The guy that built my motor had the first cam go bad. so he got another regrind and now he was telling me that the pushrods are not long enough so he put stack adjustable rockers on and has them all the way down. I bought the new cam so i can run the stock hydraulic valvetrain. This is the second block ive had since building this motor cause the first one i purchased off craigslist was a used 30 over block with a hone job and was sold to me *** a fresh 30 over bore. so i had another block done. Ive had alot of bad experiences with this car.