How to make the excerpt_more filter apply to the actual post excerpt?

I’m going to assume that you’re calling get_blog_excerpt() in your template somewhere?

If so, what happens if you simply call the_excerpt(), and then pull the two add_filter() calls out of the container function? i.e. functions.php would just look like:

function ce4_excerpt_length($length) {
    return 150;
}
add_filter('excerpt_length', 'ce4_excerpt_length');

function ce4_excerpt_more($more) {
    global $post;
    return '...<a href="'. get_permalink($post->ID) . '">Read More</a>';
}
add_filter('excerpt_more', 'ce4_excerpt_more');

And in your template, you would just call the_excerpt().

If that works, then I suspect the issue is that your filters aren’t getting applied – probably due to being wrapped in the container function.