Paint that is.

I'm putting a bid together on painting some fresh plaster walls and ceilings. I rarely ever see new plaster, and recall several years ago getting spanked on materials because the plaster was very thirsty and sucked up almost double the primer I had estimated. Does anybody have a decent/accurate spread rate for an acrylic primer over fresh plaster? I usually use 300 sf per gallon for basic drywall, but know that this plaster is going to suck in way more than drywall would. TIA