Different boat than mine (so you should probably wait until other 27 owners weigh in), but I had the same problem when I bought mine several years ago. The surveyor even included in his report "no fuel guage". However, a few weeks later I did notice that a dial gauge is on top of the tank. For my boat, there is a inspection port which needs to be removed in order to see the gauge; and I need a flashlight to illuminate the otherwise dark area.
If you don't have a gauge like mine, sounding the tank could give you an estimate. Presuming that you can see/reach your fuel tank, measure the distance from bottom to top. Tie a small weight on to a very strong cord. The weight should be rounded not "sqaure" so it doesn't become stuck on something. I've used a socket from a wrench set -- or a fishing weight. Feed it into you fueling tube slowly until the weight hits the bottom of the tank. Withdraw the cord/weight and measure how many inches of the cord is wet.
Have fun with you new boat.