The timing mark can go up or down @ TDC it doesn't matter.

But it is a lot easier to set if you put it down. That way you can see it.

Also there is an oil hole in the intake cam lobe that aligns with the intake lifter hole when the timing dot is straight down.

You can use the small end of a push rod in this lifter guide hole to locate the cam while you set it on the engine at TDC.

The small end of the push rod goes towards the rocker arm during assembly

The valves are adjusted .002" to .004"