I found this today when I opened up my intake. Any ideas how to repair?

 

I haven't run in to that problem but take a look here if you haven't seen it already ....

Intake Manifold Workshop

read through everything and i think the original poster to the site got replacement screws from Germany, however you might be able to find a replacement manifold from a salvage yard and replace the whole thing and then repair the original when you have the time...