you would need to know the drag coefficient and I wouldn't even hazard a guess at what that car would be.
That said, I recall a C4 Vette that ran the Silver State having difficulty clearing 190mph with ~500HP so he messed with mirrors and louvers and so forth to get the car working better aero-wise. Big Red cleared it with a bit of a brick and it took over 700HP IIRC (it is up over 800HP now, but original version was something like 750HP IIRC). So I would guess with a brick like that somewhere around 700-750HP to get to 200mph.
couple links to mess with
http://www.bobnorwood.com/300%20mph%...nd%20Power.htm
http://www.trackaero.com/factors1.html
if you assume the square ft square plate, just measure nose from the ground as a rectangle, add the windshield as a rectangle and see how many square ft that is. Multiply that * 71 HP and that would be a worst estimate I would think as square plates are horrible for drag of course.