Biggest mistake ever- lunati cams
Regarding what will fit without additional machining, I fit these Comp single springs w/dampers to the Speedmaster heads using the retainers and spring locators that came with the heads.
Only needed the correct sized shims to get the installed heights spot on. No milling or machining needed.
Had to measure what I had, determined what I needed and proceeded to check the specs of what was available to make it happen.
Single Outer Valve Springs: 1.476" O.D., 1.062" I.D.