shoulder belt anchor location?

Well, it looks like maybe my car never had a threaded hole for the seat belt bolts? Is this possible since it's an early 68 model? I just have a fairly large hole, one I can fit my thumb through, on the bracket. Or what I presume is the bracket as my headliner is still mostly on.

Anyone have a suggestion as to what I can do to secure the seat belt bolt to this?

Thanks!