This sounds vaguely familiar. It was like you say the block face could be distorted using a particular type of studs, however I was also under the impression they were the most common. Again it could be isolated incidents but I heard it from a good source.

I didn't take the studs out of my block to change to this method ( the idea being I would remove the studs, use a lathe to machine of the flange on the stud, then re-install using he different block face seal) - I based that decision on the fact the block had been fine for many miles and didn't want to disturb it.

I'll see if I have a photo of the seal