See if you can strip stuff down to give more access instead of removing the manifold.

You are highly likely to encounter more sheared studs removing the manifold. I was lucky that I only had 1 snap on me. Drilling into the head to helicoil / go up a stud size is a whole new world of pain.

But if you are taking manifold off, may be worth skimming the surface & upgrading the studs whilst there