[Accelo]

"He said the owner before him dynoed the truck at 400hp or so. I have not dynoed the truck but honestly it doesn’t feel like 400 hp."

Everyone has a Corvette Motor and 400hp. It it isn't backed by documentation it's BS.

I have never had a Tuner inquire about cam specifications. The motor knows what it needs and the Tuner just provides what it requires.

If you are lucky you may be able to identify the cam by the identification on the end of the camshaft. For your HP goal you will need to know for sure what camshaft and springs you have.

When you purchase the heads Inquire about which camshaft they recommend. They will have a good idea what cam to purchase, with the heads, and likely motor dyno sheets to help you out. They will help you with the compression ratio also. You will need 11:1 compression ratio and and a rev limit of 6500 or better.
475-485 at the RW is a lofty goal but not out of reach. I like to pick my camshaft and then purchase the one under it in size. That has worked well for me.
Anything over 400 RWHP will be a sh@t show unless you have tubed the truck.
Drive fast and take chances!
LOL.