The first problem is the main problem to a point so bad I onky pray it isn't time for a near complete and total rebuild and/or repurchase of parts. Since a decent machinist would have looked things over before sending it out the door.
Who's solid lifters are being used in what year block?
Some blocks have taller tappet bosses then others.
Some roller lifters have oil bands to high on the lifter that will cause it to leak oil like a gun shot to the neck.
Was any work done to the tappet bores?
There's a lot to cover here.