148-to-141 conversion effect on spoke length?
The PCD of the hub flanges cannot be changed. but the flange offsets might be. What might happen is the hub body is shifted left or right relative to the centerline by the axle conversion. 

The offsets are easy to measure, a millimeter scale ruler gives sufficient accuracy. Try this page: https://leonard.io/edd/howtomeasure. I'd personally check the published measurements anyway.