Farmer's reducer will work. Use the proportional recipe, which involves soaking the negs in bleach, and then transferring to the hypo. That way your contrast won't go out of sight. Try a throw-away negative first, then do the real thing. Also remember that you can always bleach a little more, but you can never bleach a little less after the deed is done. Go slowly and carefully. Here is a good formulary page :

Use the second recipe (proportional)

Naturally, I have NEVER overexposed a neg or processed it incorrectly, but I AM TOLD that this works very well. And I have the negs to prove it.