Thanks Greg,
The original gaskets identified in the TSB with arrows ("showing the crimped construction") did produce a buildup of rust on the block deck at each of those locations pointed to. Those small areas of rust build-up need to be removed, probably by first carefully scraping them down to block deck level.

Once I'm close to the end I'll make a list of the special and common tools that were either necessary or made the job easier. I'll also have some tips that'll make it easier, safer and produce a better result. I'd loan them all to you, but I have yet another LB7 to do once this one is back on the road. I'm sure it's punishment for something...