Transmission can easily be shimmed with plastigauge.
The factory crankshaft shim tool requires you to use an OEM case gasket (the standoff and cylinder are different lengths). I drew a modified tool in autocad that allows you to use any gasket.
The standoff and cylinder need to be precision machined/ground. I think it would likely be cheaper to buy two machinist blocks and a nice depth gauge (also a much more versatile option/tool).
Would need a large run of 50-100 to bring cost down (unless someone is willing to work for cheap). (edited)