The Bolt Cyclone PP-310 should be compatible with the Nissin i60a for Fuji when it arrives in June and is $100 cheaper than the official Nissin PS8 power pack. If you are in the market for a flash battery pack the Bolt Cyclone is worth a look at $200 off.
“The Cyclone PP-310 Compact Power Pack for Portable Flashes is an affordable, reliable and lightweight power source that works with most hot shoe and handle mount flash units that have a high voltage input, such as Canon 600EX-RT, Nikon SB-910, Sony HVL-F60M and select Metz units.”