magnum valve train questions

My 17 year old son just got a 2003 5.9 magnum and wants to use a Howard's cam with .555 lift at the valve. I know the stock springs wont work and the retainer to valve guide will need to be addressed. Is there anythng else that won't work? Rockers for instance...

Does a machine shop need to work on the retainer/guide clearance or can I grind and deburr?

This project is completely funded by my son so we are trying to cut as many corners as we can but keeping it reliable.

Any thoughts on the valve train in general considering the amount of lift?