It would be 137 before and 68 after, I think. On the down stroke you want to have the intake closed long enough for good case pressure to accumulate and not just spit back out the intake prior to the transfers opening, so it makes sense that it's open much longer BTDC than after, right?
Maciek - what you're saying about blowdown makes sense. If a kit doesn't come with instructions, there's obviously a way to calculate the optimal timing based on your particular cylinder's porting. I'm just trying to get a sense of people's numbers based on their specific setups and how they've performed. That vespa-ciao.nl thread is pretty helpful; I haven't actually calculated my timings yet but it will surely help when I do get around to splitting the cases.