Hillco has high quality header conversion kits. Check out there web site and give them a call. If you have a 925f with the old drive I believe all that you would need is a set of PTO drivelines which would cost you $450 for the pair.
Don't forget that you'll need to update the electronics to the new potentiometer system. The Dial A Matic electronics won't work with your 50 series machine. Your dealer will have to find the correct kit, based on the serial number of the platform.