Yeah I know the rear main seal leaked probably long before I got it
I just kept dumping oil in it.
I'll either get this engine rebuilt or get a built 350 that I know someone has in a Chevelle for 3,000. I'll look into those shims and post back eventually with the lifters out. I might even take the oil pan off if that isn't too hard and check if everything is tight underneath. If anyone else has anymore ideas I would be willing to try them.