My opinion,
Have a GOOD mechanic check out the engine & drivetrain on both, and really inspect the frame,
undercarriage, suspension on both cars.
The 442 pulling 500 horses may or may not have been run hard, and 500 hp cars have been known to wreak havoc on frames due to stress. If you have access to a good body/frame person have him check these cars also.
I know its hard to co-ordinate this on an item that is for sale on the open market, but will be worth losing a car than being out 8 large and having a money pit for a car.
IMHO.