Lots of categories and one template.

Hello,
i have large number of categories and posts assigned to categories. All of them need to share one template because its same design for all. How can i make one template for example clocks-template.php and change introduction text and template for each category i want and of course change list of posts on that page. So for example i have Category Barographs and few clocks added to that category. I want to create page called Barographs Landing Page. Then choose clocks-template.php have unique text and title and display categories ONLY from category caleld Barographs.

Thanks