[NO SLO PK]

Fostang, you can notch the pistons without disassembling the short block. I had this done on my old engine while it was still in the car. Iskendarian makes a special notching tool that uses a junk head as a guide. The Isky tool is just a grinding bit, in the diamteter of a valve relief. The tool fits inside the valve guide of the scrap head. Connect the shaft of the Isky tool to a 1/2" drill, and you've got your valve relief cutting tool.

The piston has to be brought to TDC during the grinding. You might lose a gram or so of engine balance. The alternative seems to be disassembling the short block and sending the internals to a machine shop for cutting and balancing.

Hope this helps.