WordPress menu to change page title

@Michael is right using wp_nav_menu() is the easiest route to go for this. If your menu (with your server problems) is only allowing to show 100 items you could consider splitting it up in to two menus.

Using wp_nav_menu() is the easiest way to go and creating two menus using the label atribute is equally easy.

First you would register the menus. This code gets added in your theme’s functions.php.

// This theme uses wp_nav_menu() in two locations.  
register_nav_menus( array(  
  'primary' => __( 'Primary Navigation', 'your_theme_name' ),  
  'secondary' => __('Secondary Navigation', 'your_theme_name')  
) );

This will register two menus. Then put this where your menu is to go in your theme:

<?php wp_nav_menu( array( 'container_class' => 'menu-header', 'theme_location' => 'primary' ) ); ?>
<?php wp_nav_menu( array( 'container_class' => 'menu-header', 'theme_location' => 'secondary' ) ); ?>

Then style it how you want so that they work seamlessly together.