Luckily, sago palms, like all cycads, can be moved, and transplanted, easily. And no, you don't have to take out a huge rootball, you just need the trunk, and the roots. This is how you do it:
• Cut off all of the leaves. Yes, all of them. If a plant has been in the ground for many decades, you may be surprised at how much cutting is necessary. Wear gloves, the leaves are sharp. What you will end up seeing will look like a pineapple, or a torpedo.
|Sago palm "torpedo".|
I left a couple of leaves on, but they dropped off almost right away
• Set the pineapple, or the torpedo, aside in a shady spot. Give it a couple of days at least for the roots that were cut to heal over. Don't be in a hurry, it can sit there for weeks with no leaves and no dirt.
And there you go. Prepare a planting area, using cactus potting soil, and it should start leafing out right away, as long as the weather is warm. If it doesn't, hang on until the next season. If a lot of the roots were lost moving it, it may take more than a single season for it to leaf out.