calculating feed of head on monoflo

I am attempting to calculate my feet of head to decide whether or not I need to use a P/S system for my new boiler setup. I have never calculated it for a mono-flo type of piping layout. I am hoping some of you fine people could assist me in this.

I have a single loop (for now) serving my entire home (see plan attached and here). Do I calculate the entire system as a single number or should I only calculate the longest half of the loop?

I am contemplating installing radiant heat in the basement and am wondering if that will impact whether I'll need P/S also.

As always, thank you.