On page 58 of Creative Black and White Photography, Les McLean describes what he calls the "Dilute Developer/Fast Film" method. It involved exposing frames of the same roll of 400 speed film at IE 400, 800, and 1600.Then he writes, "dilute Kodak D76 at 1 to 30 instead of the normal 1 to 1 or 1 to 3, pour in the tank and agitate by inversion for 5 minutes. Place the developing tank in a water bath at 24 c and leave for 6 hours without agitation, then fix and wash as normal. The negatives will show good sharp grain and will print beautifully."
I have no idea if this will work in your situation but you may wish to try it.