I think it is good to push the boundaries sith grafting and hybridization and don't think conservative members get agitated by much. It is also easy to get intoxicated by the romance of the possibility of things that unlikely. When you look at the genetic maps for Artocarpus relationships with a view to grafting compatability you can guess what you have the best shot with.
One pretty good study did trial of grafting jacks on to different rootstocks and looking at survival at 6 months. It also looked at survivors for how worthwhile they are.Cleft grafting was found to have the best survival rate. Specialist Jack grafters achieved almost 70% success with jack on jack and as high as 50% in some trials with jack on chempedak but usually lower. Jack on marang did pretty well with around 20% survival, 10% for breadfruit and 0% for camansi. 0% for all other species tried.Delayed incompatibility wasn't looked at and fruit productivity wasn't well considered either.
I wonder How close Osage Orange moraceae family is to Jack fruit (my seelings are for Che fruit)
Interesting it's Native to Louisiana , Texas, and Florida , but grows here -20F -28C
I always had a idea to take trees, and keep stressing them every day with cold to see what Happens
I doubt JAckfruit would work but thining Tamarind (in pea family) might come around. -- or Honey Locust graft.
Maybe trick the plant next generation of seeds to produce early but not grow in a cold place instead .
(did see a mutant avacodo though from another stress I accidentally put it through.
just seemed like a green stick no leaves just sand like sized for many months, but still alive)