Thats a little under 67% attenuation. White Labs says WLP028 should get between 70-75% attenuation. So you are close.
If you wanna try to dry it out some more, I would make a small starter with a pack of US-05. Wait until it reaches high krausen and then pitch the fermenting starter into the stuck wort. During the process, I'd try to keep the temperature as stable as possible too, ideally at 70. I have had some luck with this in the past.
The 5 degree drop at night may be what stopped your fermentation. Yeast will drop out pretty quick near the end of fermentation if the temperature drops, especially at the tail end of a big beer like that.