1" or 1.25"...How can I tell the difference?

[motiveauto]

I bought an 84 front end and I am getting read to do the swap...I plan on getting 6 lug rotors so I can keep my wheels/tires. But in order to get the rotors I need to know which ones they are. Does the 1" or 1.25" refer to the thickness of the rotor or the top hat looking protrusion where the lugs attached? Is it possible to use 88 and up rotors on my 84 spindles?

And one more thing has anyone used a manual dual master? I dont want the booster, any suggestions? Any help is greatly appreciated.