I don't mean to marginalize your terrible experience in any way, but based on the photos of that crack it appears to be exterior to the sealing surface, and only affects a portion of the threading for that fastener. Looking at the scenario retrospectively (which is easy to do at arms length, I acknowledge so feel free to hate me), I would have likely attempted an in-place repair and seen how things went rather than replace the entire engine. As long as you could achieve proper torque on the fastener (perhaps using a longer bolt as permitted by the depth of the threads to accommodate suitable thread engagement), I wouldn't see an issue with achieving a proper pan seal.

Now, understandably your mind likely jumps to "well, what else could be wrong though" and that is a totally valid question to ask. How damage like this would occur in the first place is beyond me, unless the block was damaged prior to or during assembly.

Glad you were able to cut the costs down significantly through leveraging your network of contacts.

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2009 E70 N62 Titansilber Sport
2000 E38 M62 Schwartz II Sport
1997 E36/5 Schwartz II M-Sport (gone)