About 1969 a friend told me that if I wished to push ANY B&W film, all I need do would be to add 1 min. 25 seconds to my developer time. It has worked for me many times and I am certain that another 15 to 20 seconds would NOT hurt, depending on how much contrast you wish to add/subtract. This is for a one stop push, of course.(posted 8593 days ago)