1. Dig out a very large checkbook.
2. Consult a nurseryman or landscape contractor will bona fides in moving large old specimen plants.
3. Expect that large checkbook to become much lighter.
4. Move plant during dormant season.
That prescription is only partially tongue-in-cheek. A 20 year old specimen of this species will likely need an 8-10 foot diameter rootball to have a chance of surviving the move. There will not be a guarantee. You will want to have prime growing conditions for wherever you decide to move it to, and plan to give it exceedingly tender loving care for the next decade in order for it to re-establish all the roots it lost and try to start growing at the rate that it had before it was moved. It could die during any of this time. It will likely shed a goodly amount of the branches that came with it during the move, as it tries to balance its resource uptake with how much of its canopy it can support.
You could post some pictures of your plant with which you cannot bear to part. I suppose I will chuckle a bit when I see it, but I understand the connection. I also understand the difficulty in attempting this feat to defy nature, as that is man's want. I spent a dozen years in a career moving very large plants in my employment - but I had a crew of 5-10 to help take care of such plants.
Where you live, there are many horticultural professionals that will likely tell you this same tale, but will gladly take your money should you wish to pursue the effort.
