How much would it cost to put a new camshaft?

Also wanted to know the cost to make it have 500hp. Parts/Labor.

This video series can help you build the 500 hp engine and what the cost would be.

https://www.youtube.com/watch?v=NyX6FwLYDuc&list=PLe3kz1i_LrtX5402mzO6ovoz8xeUdwZ8B&pp=iAQB

Just to install a new camshaft the labor is

Camshaft, Engine 15.8 HRS@ shop rate

and the OEM camshaft would be

Camshaft 12560967 $740.85

there will be gaskets and oil, filter and coolant as well so add a little more and you should be close. Also, they will want to replace the lifters as well

Valve Lifter 17122490 $57.50 x 16 = $920.00

Let us know if you need anything else.