So from what little I know about jackfruit, it’s kinda soft, not really dense, kinda elastic, and pretty easy to work. I don’t think it’s absolutely useless but it might reach it’s limits sooner than you expect. A long PB’s a smart choice, keep it wide, keep it long, keep it from blowing up. Probably for the best to stick the the 30’s in terms of draw weight. And regarding weight, it’ll either even out with time or not, don’t think it really matters too much, a tree isn’t all too uniform to begin with. Best of luck to ya.