Originally posted by 76GMC1500
Each bank has its own lifter oil galley which is also where the head gets its oil from. If the rear galley plugs are set too deep, it will block or restrict the oil flow to every lifter, pushrod, rockerarm, and valve on that bank. If you start the engine again without doing a complete rebuild, do ensure you have oil flow to that bank. I would recommend you check the lifters. You will have to pull the intake to do this.

Are any of the valves seized in the guides?
Yeah, what he said