Huh? Where do you get your information? There was about 6 to 8 sterndrive 28s made, max. They were made from the old Cobra hull, which was derived from the 27 Magnum and 28 Cigarette hulls.
There was never a 28 hull mold, the 33' was dammed. There was however a dedicated 28 deck mold.
Your Powerplay is an excellent boat, made well and will take a beating. By '99 all the kinks had been worked out of the hull so it'll track straight and fly right if you're trimmed properly.
As you've probably already found out, the boat responds well to trim, just a little adjustment here and there and the hull will respond quickly. Tabs are usually just used for getting on plane and leveling out the boat in a cross wind.
I miss my 33' like crazy, but there's always another boat.