I would reccomend seam welding the side engine mounts before sand blasting especially if you are planning on a moderately more powerful motor, mine eventually broke due to no apparent single cause on then RSI
I would also try to make up some ineer gaurds (assuming you dont have them already as muck tends to get up behind the indicators and this really starts the rust.
Golfboy the I can answer the question to your GTI comparison, the GTI will lose. These are great driving cars
Good luck guys you will be well rewarded with the end result