With the help of my friend Steve C. we got some measurements to compare the GHQ Puma with the actual vehicle.  The dimensions for the actual vehicle are from Wikipedia and I assume they are pretty accurate.

Notes: The height measurement from the GHQ model is from the ground to the top of the turret.  The width dimension for the actual vehicle is the up-armored version.

Key:
Column B = actual model dimensions in inches
Column C = model dimensions multiplied by 285
Column F = Actual vehicle dimensions in inches
Column H = Difference between GHQ’s model and actual vehicle

Conclusion:

It seems that the GHQ model is just a little bit too long (9.34 scale inches), WAY TOO wide (33 scale inches too wide) and WAY TOO tall (37.55 scale inches too tall).