Are you in the southern hemisphere? The grape may be dropping leaves/going dormant soon. Best way to move feijoa is take as much of the rootball as you can.

If it is mid-autumn there ( ripe fruit on ground ) the timing is decent for a move, but a rootball large enough to have a chance of success would weigh hundreds of pounds. A 2-foot radius and 2 feet deep minimum. Can be done with several people and a tarp for dragging to new location.