Override header-args property for a code block

[Naresh Gurbuxani]

At the time of export, my default is not to evaluate code blocks.  But I
want some code blocks to be evaluated.  For example:

#+TITLE: Worg Setup
#+PROPERTY: header-args :eval never-export

#+name: years-since
#+begin_src emacs-lisp :exports none :var when=1985 :eval yes
  (number-to-string (- (string-to-number
                      (format-time-string "%Y" (current-time))) when))
#+end_src

GNU Emacs has been flourishing for call_years-since() years.

Export to latex (C-c C-c l p) ignores ":eval yes" setting.  Commenting
out PROPERTY line, then reexporting does evaluate the call and replaces
it with 40.  My org-confirm-babel-evaluate variable value is t.

What changes are needed in above org document?

Thanks,
Naresh