Nah, your standing forces will soon suffice to integrate them without placating. Unless you feed them India, which isn't as feasible as it used to be so I'd rather not.
If you're not using support rebel CB to bypass LD there is no way. Base LD from 300 development is 75%. That's if they + your other vassals have 0 regiment and no recent events. Slap on > 100% LD from events/defections and you're going to waiting a while to annex. Grant province got nerfed into non-viability as a solo LD management tool. There are better ways to approach this:
1. Right now, making a vassal into a marge wipes all positive and negative LD modifiers that decay, so you can nope egregious levels of defection LD (and >100% LD for less than 5% of overlord's territory defection IS nonsense by any coherent standard).
2. Placate it down. Not good for > 100% events, but doable if it's smaller.
3. Just core stuff like Syria. You can't make that land trade company, it's already accepted culture due to empire rank, and you have mission claims all over it giving you 40% LA from go. You can do the same with Iraq, though IIRC I wound up getting them as a freebie OPM with vassal + force religion combo (faster annexation for same religion) then using reconquest. The two Shia religious centers took some oomph to convert w/o religious but doable eventually.
In my game Persia broke out very fast so I just fed some of it to Sunni-forced Tabarestan and cored the rest myself, no big deal. I was chasing the easy wars, especially temporarily easy wars, as a priority.
