Custom permalink for each post

im importing data from Drupal to WP. I have more than 10 000 posts. Each post have ID, category and slug. For example:

• Category> important
• ID> 11111
• Slug> hello-world

I need to keep permalinks same like they are on drupal because of SEO:

www.wordpress.com/important/11111-hello-world

The problem is that, i cant insert post with ID 11111 until is database index set to this number. If i do import, this post will actually much smaller, never the same like on drupal.

I wanted to make post-meta with old url. For example

• _oldSlug> 11111-hello-world

And then apply rule: If is set post-meta named "_oldSlug" use it (%category%/_oldSlug), else use wp logic (%category%/%postid%-%postname%). But problem is, that i dont know how to achieve it, if is that posible...

Any idea how solve this problem?