13 might be a little big for a 3, but it should spray okay. Pressure with my 310 didn't need to be moved at all for a 514-both FFLP. Start at a little over half the pressure you used before, and it might take a little more to get rid of any hard lines on the edges of the fan. They lay down, a beautifully light fan of spray, with almost no bounceback/overspray.
For those that don't know, watching from the sidelines, the first number in an airless tip size is half the width of the fan at 12", and the second two numbers are the size of the orifice. The orifice is made from carbide, and lasts maybe through 50 gallons of spray. For a smaller fan, you need a smaller orifice, to spray the same material, because the narrower fan doesn't demand the same volume of paint as a wider fan-the reason I said a 13 (orifice) might be a little large for a 3 (6" fan width). You can use almost any combination, but it makes a difference in coverage, and how fast you have to move the gun.
To spray cabinets with an airless, you used to need to get your adrenaline up like you were getting ready to run a football play. The FF (fine finish) tips eased that off a Lot, and now add the LP (low pressure) to that, and it makes it a real pleasure to use, without the demand for adrenaline.