Maximum fuse size will be in your local electrical code. Minimum size can be what you want it to be, except if the fuse is too small it may nuisance blow or simply overheat. You mention coordination, general approach is to start at the last device and work back toward the primary, without exceeding the maximum ampacity for each device allowed by code. Where do you get using 67% of the fault current for coordination? Primary fuse on a secondary L-G fault through a delta-wye transformer sees only 57.7% of the fault current, and on a secondary L-L fault through a delta-wye transformer sees 115% of the fault current. On solidly-grounded wye systems L-G fault current can be up to 125% of the bolted three-phase fault current. 67% is a new one for me.
In your case you have to consider other variables beside connected load, including cable ampacity and inrush current of your largest load and whether it could be the last load energized. Example: start with largest motor, determine locked rotor current above which your motor circuit protector has to be set. The fuse must lie above and to the right of the motor circuit protector curve up to the maximum fault current available for complete coordination, without exceeding the maximum size allowed by code. However, if the motor is started last, you have to add the inrush to the existing load current and leave more margin for the fuse. Sometimes coordination and/or protection has to be sacrificed, making this more art than science. Check out ANSI/IEEE Std 242 (Buff Book) for more info.