Do you have a bare set of heads you're building or assembled? Spring selection is going to depend on your valve length and retainer installed height. According to their website (and some information I have found out by getting some of their parts in my grubby mitts) if they're assembled heads with the dual springs without dampers and "whatever" retainers they come with, they're supposed to have a 1.85 installed height with around 110 pounds of seat pressure. But if the heads are bare and you're having them set up by someone else, all they'll need to know is your targeted build lift with required seat and a ballpark open pressure.
