You can use a source block with a self-defined major mode.
It is easy to define a customized major mode with helper functions like define-derived-mode.
Let us name your new major mode myorg-mode. Then the name of the function executed on C-c C-c is org-babel-execute:myorg.
It is called with two arguments. The first arg is the content of the source block as a ...
This was suggested to me through the org-mode mailing list: replace ‘org-tag-persistent-alist’ instead of org-tag-alist in ~/.emacs. I tried it: autocomplete works for both the local and global tag lists.