Block out of square

Build a stout fixture that bolts to the crank flange with an adjustable tool on the end, rotate the engine by hand and reface it. Presto, the bell housing mounting face of the block is now square with crank flange regardless, no engine disassembly required. Granted such a procedure could be fairly time consuming, likely requiring light passes, but as opposed to what? Complete disassembly and a trip to a machine shop plus reassembly time, or just starting from scratch with another block?