fuel tank placement - 23 center console

[thedink9]

Come on guys(and gals)! Does anyone know how to calculate how far aft I need to move a 96" long 131 gallon tank That I usually run half full to transfer 200 lbs to the transom?. I incorrectly moved the new tank 4 inches forward in an attempt to stop the boat from being too stern heavy and now the CG is too far forward. Thanks Rich