The 32/34 dmtl was fitted to 1.6 (xr2/xr3 iirc) so its as much a 1.6 carb as the 34 IBF will be.
Given the 1.4 is about as far from a performance engine as you can get, personally I'd just fit whichever is in best condition. May need a tweak in the jetting, but that kind of thing should always be checked even if a carb is designated for a particular CC