Like your thinking. Had a few 130 and a 136 and a 135. Never had the balls to cut the roof off and the cars are quite rare. The 136 had the split drive shafts so handling problems sorted.
With a few tweaks and the group b exhaust and carbs the road car ran out of gearing at 125 odd.
Skoda Rapide cab?
Or would that just be silly?
As you may have noticed I quite like cars with the engine at the back.