(((Hugs))), Jenn. I've just seen this thread.
FWIW, we've gone through some developmental stages, coupled with some OT, that has led to that LOOONG time to fall asleep at night.
Are you sitting in his room at nap time too, or just bedtime? I was just thinking that maybe you need to work on getting out of the room before you do any major schedule tweaking, as if that's different for him, it might be a factor in the length of time for him to fall asleep?
Another thing I noticed was on the day he took a 1.5 hr nap, he fell asleep at 7:45 pm, but then on the day he did 1 hr 20, you had him down for 7 pm. Maybe 7 was just a tad early and he ended up missing his window and becoming OT? Just throwing out some ideas for you.