Questions about coolant refill....

[Vette73]

In the process of putting car back together after bad starter and porting IHs and plenum.....

I must have taken out around 3-4 quarts of coolant prior to work.....
I'm reading now it can be an issue when you refill coolant (what else is new)

Forgive me I'm a little old school.....I'm reading now the car has to be jacked up for it to flow maybe? Maybe there could be air in the lines?

Maybe it's good I read about this before I replaced coolant because all I was going to do was replace and that's it.....Now, if there is an air pocket it really wouldn't show right away on the temp gauge and the head gasket can be damaged...

Could somebody explain this easier than all these articles I'm reading?
Maybe a photo......I have an idea what to look out for but want to be positive about it....

Thnx again....