I got the motor out and measured a few of the lifter bores. The one where the lifter body cracked is .0009 out of round, but very little taper. It measured .9055 parallel with the cam and 9.064 perpendicular to the cam. I measured a couple others and they were a couple tenths smaller, but also out of round. I was worn out, so I only measured a few.
I measured one of the good lifters and it was .9035
So I have about .0029 clearance in the thrust direction.
After Talking though PMs with a member, it is possible that the loose clearances caused the lifter to be out of plane enough with its paired lifter that it eventually caused the body to crack and fail.
We will save this block until I can obtain a Lifter Tru.
We will just start with another block, after thoroughly checking it of course. we have several blocks to choose from.