Blackcoog
Hard-core CEG'er
Picture 1: The area that has to be (or at least in my opinion) hogged out to allow a bolt to pass. You have to seal the gap into the bellhousing beforehand. I used urethane.
Picture 2: Big fender washer used to provide clamping force.
There are 2 spots you need to seal as well one is pictured in the second picture one is a few inches above it.
There's one more I'm going to be drilling a hole for to allow the right side of the lowest oil pan bolt hole to be used.
BTW you don't need to seal those gaps. It doesn't need an air tight seal. There isn't any fluid in there.
If you are that worried about it you should have removed the 3L pan and pickup and swapped over to the 2.5L pan and pickup which will allow you to use the bolt holes like normal. Of course you need to modify the 3L windage tray and install a stud for the 2.5L pickup but that isn't that big of a deal. Probably less work than what you are doing now though.