Can I get just a little more power??

[Water Warrior 2]

Peanut. If possible do you have the opportunity to take a run at the hill at 60 or a bit more? 60 will be closer to max hp and torque of the engine. You will still likely slow a bit but not down to 50.
Lynda had the same situation with her GZ. A long grade that she more or less conquered with speed. Hit the bottom of the hill at max speed and slowed to 50 at the top.
Her M-50 could start at the bottom at 50 and a slow twist of the throttle could easily top the hill at 100. There is no substitute for displacement. Use the throttle when needed or gear down and maintain the speed of 55 going up hill. And yes, the GZ will sound like a potential grenade but it will hang together for the odd hill. A steady diet of high revs will give it a shorter life span and repairs.