6.2L turbo for K30 project

[Deercreekfarm]

So started the rebuild on the 6.2l  engine for the k30 project. While I was tearing down the engine I noticed it had the block stamp number of 14022660 and instead of a date code it actually has a date of 10-29-81 below it.

Then beside that near the top center of the  block there was this symbol.

Can anyone give me some insight to these codes especially the one in the top center of the block?
I did read somewhere that the blocks with the 10-29-81 stamped blocks are very desirable but they didn’t say why they were so desirable?

Thanks,

[Deercreekfarm]

No input guys?

Well I got it broke down pretty much the whole way. I’m going to send it and the heads off to get magnafluxed then decked.
This engine will be getting a GM8 turbo so I’m still debating on weather or not to use 6.5L heads?

[fitz]

I've read that the "red" blocks used on the 1982 6.2's are desirable.  I'm guessing maybe it's a higher nickel  content?

[Mr Diesel]

I was not familiar with the red block theory, so I googled a bit and came up with these links which had mixed replies from 6.2 diesel owners. Some of these threads are a little old now. Lots of people saying the 1982 red block was stronger due to higher nickel content, but no actual concrete evidence and possibly attributed to urban legend (but not necessarily false).
https://www.thedieselpageforums.com/tdpforum/showthread.php?t=40646

https://www.thedieselpageforums.com/tdpforum/showthread.php?t=41797

https://www.thedieselpageforums.com/tdpforum/showthread.php?t=38874

https://www.thedieselpageforums.com/tdpforum/showthread.php?t=6621

I could not find anything about the stamping digits in your second picture.

On a side note, one of the threads recommended Clearwater Cylinder Head for good quality block / heads (supposedly Chinese imported from Canada, but 5 year warranty on heads).
https://www.cylinder-heads.com/?s=6.2+diesel&dgwt-wcas-search-submit=&post_type=product&dgwt_wcas=1