On your first failed long blocků.
Based upon your comments and your description of the engine failure, which appears to be catastrophic, I find it difficult to understand what parts were used, what machining was done to the block, and who assembled the long block? Did the shop rebuild the long block or did they buy it from and eBay supplier and sell it to you?
On your new rebuilt long blocků
What specific machining was done to the block?
What new parts were used?
Other than NPR rings, whose parts were used?
Was the head rebuilt or new?
What camshaft was installed and what valve lash was set?
Did this shop recommend a break-in procedure?
How many miles on the break-in now and how much oil is it using?
What are the engine specs and all parts used?
What oil are you using?