Lambic Wyeast 3278

I am planning on brewing a Lambic tomorrow.  I am going to ferment in a 5 gallon glass carboy using Wyeast 3278.  This is my first time using this yeast. I’m wondering how aggressive the early fermentation will be.  How much headspace should I leave?  Do I need a blowoff tube?  I am planning on pitching and leaving in my basement at around 60-65 F for 12 months or so.

7lb Pilsner malt
3lb raw wheat
turbid mash

It’s pretty explosive. It has several Belgian strains and they will ferment aggressively the first few days. Personally I would plan on 0.75-1 gallon’s worth of headspace and use a blowoff the first two or three days.