I'm afraid the answer to the difficulty in removing the liners from 1 and 4 is due to them having picked up during a severe overheat.
The liners have been hammered into the now annealed block, and where the trepanned mating face is, the block has been distorted where the liner has hammered itself in effectively peening the area.
This is why the liners "drop", they don't in practice, they have simply deformed the newly annealed block.
I suggest this is the point where a replacement block is sourced, shimming the liners is not a cure for a block which has been overheated to this extent.
If you do decide to carry on, you will find the liners will "sink" again, this is especially true if a MLS gasket is employed as part of the repair.
Brian
