Rebuilt engine starts perfectly, then comes to screaching halt

[TheDude7B7]

Fellow Afourians-

Finally fired up my engine after a 3 year rebuild project (thank you COVID and other stressful life events). She started and ran flawlessly, idling smoothly at 850 rpm wth 40psi of oil pressure. Then, to my dismay, two minutes into the first run the engine came to a screaching halt. After the engine stopped, turning the crank resulted in a squeaking noise. Video links are below. After the engine cooled down, the squeaking went away. Engine started up perfectly again with the same result.

Has anyone heard this noise before? It's gotta be heat realated and I'm thinking it might be some oil startvation. It sounds like it's coming from behind the flywheel or the #1 cylinder.

As far as the rebuild, I had a machinist bore the cylinders 20 over, turn the main and rod journals. I also had him do the assembly with new pistons, rings, rod, main, cam bearings. Could this be due to a lack of end play? I'm stumped and really want to exhast all possibilities before I have to pull the engine again. ANy thoughts would be helpful.

Video of engine seizing:
https://youtube.com/shorts/PfYWaLNe4d4?feature=share

Video of turning crank:
https://youtube.com/shorts/xjDrVXxh-Rk?feature=share