That's awesome work for sure. Congrats, man.
Thing is though, dropping 70 pounds in 3 years is slow (albeit steady) progress for a bigger guy. Were you a kinda-muscular 265 or was there another issue along the way? What's your current condition: lean-ish, soft, something else?
Low carb diet, low carb diet, and low-to-moderate carb diet. Not critiquing, just pointing out that it sounds like a long time since carbs have been a significant part of your diet. They can definitely be beneficial when you get back to bulking, but remember to take it easy and gradually incorporate them.
It depends on a few things. Your current condition/bodyfat, your training, the nutrition plan you use to bulk, etc. If you're relatively lean/not still fat, lifting hard, doing your cardio (yes, some, even while bulking), and your eating's on point, I wouldn't stress much over insulin resistance or fat adaptation.
You're on a plan working towards a specific goal. Monitor progress on a weekly basis (strength, bodyweight, pics and/or measurements, how clothes are fitting) and adjust the plan as needed, just like anyone else.
But in general, since this is a "general nutrition" thread, yep, I'd say bump up your calories in smaller chunks, a few hundred at a time. Then see how it goes, and adjust as needed. The other big key is to make sure your strength is increasing pretty much across the board while you're gaining bodyweight. That'd be a decent indicator that you're building muscle along the way.
Check out these articles for some probably-relevant and useful points:
Or if you're digging the paleo plan in general and want to tweak it a bit: