How Can I Correct Low Riding Stern

I have a 1998 196 FishnFun that I have restored. I had to completely replace the deck and stringers which I did using 3/4 inch resin coated plywood. I replaced all of the seats since the originals were in terrible shape. I kept the original helm and recovered the livewell seat cushions. The problem is that the stern rides so low that water comes over the transom and enters the steering cable and engine operating cables/wires openings and floods the bilge. Engine is the original 1985 Johnson 150 OB which is what is rated as the maximum for this boat. As far as I know I have not changed anything weight wise from the original design except for replacing a badly leaking 24 gallon aluminum fuel tank with a plastic Moeller 27 gallon. However I did remove some bad foam that was located in the stern when I replaced the fuel tank. I also repaired and sealed the four hooks on the back. Any suggestions as to why this is happening or what I can do to correct this problem?

Thx John