Boom truck or overhead crane works best. Gives you better access. If it is an older truck, it might be wise to consider doing both, if one is blown.

working on any mast is not all that hard , the most important thing is to have the correct equipment and use extreme caution when removing any component.
You will need a hoist of some sort, chains and blocks or lifting straps. Something to catch oil in and also to absorb whatever spills onto the ground/floor.

On such a big mast i would have a second person there to help out even if it is to just be a spotter for you.

If you were to give a truck serial number and type of mast that is on the truck it would be more helpful. 2 stage duplex? 3 stage triple? pre 2003?