I did what you are thinking. Dug up a large one, planted it in my yard. It make all the seed I can use for rootstock. It smells great when its blooming. It is laden with 4 inch thorns and really interesting plant. I keep it pruned so it does not get out of control. I have grafted Flying Dragon on it and several other rootstocks. It is an all purpose rootstock tree and an all around interesting specimen. If you do this: Wait till the poncirus has shed its leaves and is dormant. Dig it up and replant in your chosen location. Water it good. In Spring, if you have dug up a tree old enough to bear fruit ye shall be blessed with fragrant blooms and golf ball size fruit that will turn yellow/orange about September. You can then graft onto it, get seed for rootstock and enjoy the tree. Keep it pruned like you want it.