As regards to correctly bolting the flywheel to the crankshaft, people are being advised to make sure that #1 cylinder is at TDC on the COMPRESSION stroke.  While not wrong, it is irrelevant at this stage of assembly.

The Willys L-134 Go Devil crankshaft is arranged such that #1 and #4 rod journals are at equal degree position on the crankshaft, while #2 and #3 are also at equal position, but 180º opposite from #1 & #4.

So if #1 piston is at TDC, then #4 will also be at TDC, and the timing marks should show through the opening on the backing plate.

If the flywheel has been mounted 180º off, then the timing marks will show up when #2 & #3 are at TDC.

Understanding this, it becomes evident that it DOES NOT MATTER which plug you use to time the engine from.

If the flywheel has been mounted correctly, then timing from #4 spark plug works equally as well as #1.

If the flywheel is 180º off, timing can be made from either #2 or #3 spark plug.