This is confusing you're mixing up the terminology of WordPress. A custom post type acts like a post and not a page. If you have a custom post type called "portfolio" and use the proper template hierarchy, you don't have to do anything special. But you will need to name it
single-portfolio.php and not
If on the other hand, if you simply want to use "page" templates ( I think that is what you mean) you will need to write a conditional to display the post meta for only the
The logic is along the lines of:
Your default page most likely already has
the_meta(); though so you will most likely want to use
get_post_custom so you can have fields specific to your "portfolio".
ps. It's much easier to just use a custom post type (not a page template) for this sort of thing .