For a leakdown test you will need a calibrated pressure gauge and a pressure regulator and adapters to connect it to the spark plug hole. The adapter is then screwed into the number one spark plug hole (with cylinder #1 at TDC compression) and the gauge is attached.. Not sure what your TDC will be as its a built engine with different cams etc from the stock engine.
As soon as the gauge is attached to the adapter air will begin to fill the cylinder. As this happens, the gauge will begin to indicate the amount of air flowing into the cylinder.
If air is leaking past the rings, or the valves, or the head gasket, we can directly read the amount of leakage and can easily find the leak. If there is air blowing out the PCV, you have a ring leak, if it's coming out of the exhaust, you have an exhaust valve leak, and so on...etc..
Anything past 10 per cent you need to be concerned about...
You need to do the same on all cylinders..
Lets us know the results for both...
Will be interesting to compare..
Any help Jon, give me a shout...