First you would need to map the meta class that you are using in the external_metadata.cfg in to the metadata-mapping.cfg. You can do it via the admin ui.
If we leave meta_t since you said it wasn't working, let's consider the meta class 'name';
example.com/directoryname/nameofpdf.pdf name:"Page title" d:19110101
Then in the metadata configuration map, map a new meta field and assign it to 'name'. Say 'pdfname' is the one you are creating in the metamap. Then pdfname=name
After that in the collection.cfg reveal the new meta class in the json reponse as well. You just need to add the new meta class to the query_processor_options under -SF.
e.g. query_processor_options=-stem=2 -SM=both SF=[pdfname]
Then when you check the said pdf's in the json output, you would be able to see the titles assigned to the new meta class. You'd then need to use the same in your template as Pete has mentioned above.
If you are not using meta_t, then you'd probably need to use some logic to apply the newly defined title classes to be used in the template as well.
Once you get confident on this process, you can try to assign the 'name' to meta_t in the meta map.
Hope this helps.