One thing you may want to consider if so inclined is to modify some key stock or a Woodruff key so once you find TDC and mark it, you won't have to do it the next time again if you have to pull the PMA down the road.
The crankshaft takes a 4mm Woodruff key. the PMA that Hugh sells has a 3/16" keyway. I bought the 3/16" straight key at Lowes (they don't stock Woodruff keys) and with a little plastic and wood for a fixture in my vice, filed a step on both sides of the key in the form of a fat T. Once it fit in the crank snugly, I cut it a little longer than the crank key slot and with my Dremmel, arced it on both ends to fit the crank slot, i.e. made a pie shape Woodruff key out of it.
When you go to install it, use some heavy grease to hold it in the keyway, placing the keyway straight up to make it easier and slip the PMA on. You can check with a good light on the end to verify that it stayed put.
I think the keyway will be at 6:00 when the left cylinder for a rephased engine is at TDC. For an engine that it not re-phased, both pistons have the same TDC. You need to verify TDC using a degree wheel anyway.