I do not know from experience but from what I understand about acrylic the top of the tank is very, very important part of the tank, structurally. I think it could be done, but the acrylic would have to be extremely thick to prevent bowing, and eventually structural failure. 1" is very thick for a 180g tank though if cut short enough it might work.
The tank looks like it is in good shape why not sell it and buy a rimless frag tank that was designed to be that way?