What are you wanting to do with the negatives? If you are planning on enlarging them, are you using a condensor or diffusion light source? If you are contact printing on Azo or pt-pd, for instance, that is another matter entirely.
I would suggest that you look at the information in the article prepared by Sandy King about pyro developers that is posted on Unblinkingeye.com. It will give you the density range and development times for several use considerations.