It would be a lot of work to make a car that would end up horribly tacky.
I mean...its not going to beat this.(At least, not without some serious effort and precision to time consuming detail)
To come even close to pull it off, would require cutting most of the rear of the car off from the side windows back, as well as the roof. You'd want a different quarter window, which would mean a different rear fender shape. The amount of work to make it look anything less than tacky, would be beyond most anyone, and some one with the skills to do it, could better spend their time on nicer projects.
I think starting with a cab, would be the right track, different windshield, windows, and roof line would help. Give it a "chopped" look by shortening the roof. Bringing the roof line down and forwards along the windshield line would be key to getting the rear to look some what right. Ferrari's that have that look, have very low green houses.(Btw, the Ferrari Testa Rossa was designed with a hatch, but for lower productions costs, and easier cooling, it got the chopped off rear lid instead.)