I'd at least mount it in the engine bay.. Whats that take on an mk2? 20 minutes? Saves it rocking around.. or falling on itself and damaging something.
I recently revived a 1.6 rabbit that sat outside for 16 years without injectors installed. I took a few more precautions because of dust in the cylinders, but after a couple weekends of work, the engine runs like a top and has been my main driver for a year.