Funny you asked, in the last few days another poster asked the same thing (try a search?) the rep he spoke to recommended the 150.
The hap with the scrambler/cafe project is also I think running the 150.

I happen to think that might be about right, the 140s recommended rim would be narrower and the 170 should be ok on the rim but you might get clearance issues between the knobs and the chain guard at the fwd end.

Mostly conjecture but I hope that helps.
Marcus