Bermuda Hay Renovation

I have a hay field (about 6 acres) that was sprigged about 10 years ago with Russell Bermuda, but has now been overtaken by Bahia (I live in central Alabama).  The field is too small to be sprigged again, but I would like to get all of the Bahia grass out.  I have two spots where there is good bermuda, but everything else is Bahia. 

 

What are my options for renovating the field?

Spray with Pastora (or something similar) to kill the Bahia?  I'm concerned there's not enough Bermuda to spread over the field.

Lightly disk the field?

 

I'm looking for suggestions!

 

Bermuda Hay Renovation