tbh, if this jeep wasn't so rare, I'd strongly consider moving to a non-greasable. As it is, I'm trying to keep it as close to current, or revert back to stock but with safety prevailing in the end.
Only considerations I can see for poly bushings is for climates in which they don't do well (Florida or anywhere with salty roads in the winter).
There's a gentleman named Sal Walter (not sure if he's here, but he's in the same Facebook groups I am) making parts using oilite. He's considered making spring bushings and packaging them with Grade 8 bolts for this. Might be worth seeking him out if you're planning to change.
hth