Here are some pix of the baffle on a 261 in my shop. The pictures are from the outside looking into the draft tube hole. I don't have an open block to show what it looks like from the inside.
The baffle is curved. It is snug against the block at the top and on the side where it is secured with the stovebolt. There is about a 1/2" air gap at the bottom. The baffle ends about flush with the rear edge of the draft tube hole. As previously stated, it acts as a deflector to protect the draft tube from sucking in splashing oil, but leaves air gaps to allow the crankcase to breathe.
