Would you notch a 727 bell that already has an inspection port in it?

It will be fine. Just use a good torque wrench and the longest grade 8 bolts that will properly fit and hardened washers to clamp it to the block.

How do you normally notch them? I used one of those hole saws with a small pilot drill in the center that's normally used for cutting holes in doors for the handles being sure to start the pilot hole about half the pilot bit width away from the edge of the block mounting face. I then smooth out any stress risers with a burr bit.