This old paper is likely to have fog
and lowered contrast. Recommendations:
- Use a high contrast developer
o Dektol undiluted (your suggested 1:3 goes in the wrong direction)
o Dokumol (Tetenal)
o mix-your-own following Ilford ID-14 (google...)
- Add benzotriazole @ 0.3g/liter working strength developer to fight fog and improve highlight "snap". Note: the image will be slower to appear, and you may need to extend total development time, although undiluted Dektol should be rather fast.
http://stores.photoformulary.com/-strse-373/Benzotriazole/Detail.bok
10g @ $4.95 will last you a lifetime
- Selenium tone (1:10). Will increase Dmax and dark tones "snap". Also nice in general with any paper.
Sucess is not guaranteed, but that is you best chance. If you have a fairly large quantity of expired paper, may be worth the effort.