Use a common automotive compression tester (dynamic). Leak-down tests might have been the "standard" in the industry for 100 years but the dynamic compression test is more accurate (less low end results) and should be used as the primary test.
Leak-down is useful to determine the location of the leak, but then you don't need the tester set-up, just the spark plug adaptor (old spark plug), solder a hose barb fitting on, add a short section of hose and an air line fitting (male). Then plug it in to your air supply through a pressure regulator.
The Toledo (and ToolPro) brands doesn't specify the orifice size. They are more than likely around the 1mm mark. If you need it, I can see if I can measure mine. They are available from Supercheap & Repco, most likely also from Bursons etc.
392419.pdf