I agree with the idea of re-using a tree that has been in the ground a long time and has a well developed root system. Good time to learn about grafting if you don't already know. I have a similar situation, although my rootstock taken over tree is older. I've been cutting back some of the 4 trunks to encourage new shoots with the idea of practicing my bud grafting on them. Do you remember Joe Real's citrus tree with 80+ varieties grafted onto it.

It turns out it had been 7 days bot 17 so I wrapped them up. I unrapped them today to find that 2 are good and 1 dead. I have 2 Seville sour rootstock trees left ungrafted. I will wait till next year to try. The wound to the right s the first grafting attempts failure. The other one above, below Steve

Mostly from reading. When I was a child we went through a shift of great tasting oranges to so-so oranges as we,ll as bananas. It wasn't till decades later that I learned of Tisteza and realized my youth time coincided with the triteza outbreak. That is when all the sour orange rootstock citrus trees died. The bananas, Kampala were also wiped out by disease and replaced with Cavendish. I did not read about either extinctions until I grew citrus trees. Steve

Meyer Lemon has a really wonderful strong scent. The Meyer Lemon also blooms throughout most the year even when there is fruit already set on it. The flowers are larger and pinkish purple tinged and are prettier than other citrus imo lol. My mom has the sour orange in Phoenix. She originally got it to help pollinate her sweet orange tree. It must have worked because that thing was loaded down with fruit every year. If someone has an older grafted orange tree and they wanted a sour orange, they could let a sucker grow under the graft line, let it to grow until the stem thickens up a little, then either air layer it or cut it off taking a 'heel' where its attached to the stem, apply rooting hormone, and put in perlite/potting soil keep moist etc.