Don't think there's any timing difference between the 034S and the 036. Same Jug. The standard 034 is different, with the 46 vs. 48mm bore and the presence of the intake uvula. I'm sure slight variations in timing from jug to jug may exist, regardless of bore size, like on other Stihl models.
The 034 has a deeper front air damn in front/underneath top cover that won't allow it to fit over the larger 48mm jug.
As Jason pointed out, using the standard 034 muffler with either 48mm jug will require the 034S spacer. The 034/S muffler is the older style with the ventilated heat shield over the front of it. Not sure if it's baffled internally or not. I'd personally add a 36 muff and toss the thing.
I'd use the 48mm jug because there is no replacement for displacement, as they say. If you were gonna stick with the 46mm jug, I'd port it a bit differently. There's a difference case to swept volume ratio and a relatively bigger carb for the 46mm jug.
A well ported 036 is my favorite all around Saw. I'd never get rid of mine. Mines a bit ugly but 100% badass.
