I call anything over 7 or 8 ft large just because they are, and something like yours a mature plant because of the size of the root ball and age. I would much rather have yours than an 9ft young plant!
The base of the Texas Mango mid-section was probably almost 4"s and it rooted no problem...I was amazed. I think a plumeria is so resilient that if its alive and you stick it in dirt...it will grow.
