I came up with 299 kPa gauge. I can assure you that my calculation was easier. I loathe having to do any calculations in ft-lbs, psi, or BTUs.
27.7 inches of water ~ 1 psig. Easy to do. Learned it in ME and the boiler business (dealing with flue draft) many, many years ago. It’s one of those things that just sticks with you.
Even if memory fails me, there’s always http://www.onlineconversion.com/pressure.htm to assist.