Scraptor

http://www.cranecams.com/contactus.php

^^^They can. They also have the knowledge to tell you what you need to do what you want. Other cam companies can also help you, cams are what they do.
I plug for crane because I have had good luck with them in past with my Mopar junk.
RV cam is a generic term , it doesn't mean much.

qdeezie

For a 351 with mass air, you should really consider a custom cam.

Evan96F150

Okay so I know I should get gt40p heads but what cc should the combustion chamber and intake runners be?

qdeezie

Do you have (or will be getting) the headers to clear the spark plugs on the GT40p heads?

Evan96F150

How would I tell if they will clear them?

qdeezie

I would reach out to the header manufacturer. I have heard more than once about being able to get away with standard headers and a 90 degree spark plug boot, sometimes with a boot insulator to clear the header tube and not burn the spark plug boot.

Maybe someone with P heads will chime in with what they used or did to clear the spark plugs.

Evan96F150

Will a cam for a 5.0 still work in the 5.8

qdeezie

Yes, a 5.0 cam will work in a 5.8.

Evan96F150

How can I tell if the cam and heads will work well together

qdeezie

The main thing is you don't want a cam that is too big for your application. You have a little flexibility with the heads provided you don't go extremely big since you're building a 351.