Not sure what your real question is here but that may be down to my brain at this time of the morning
afaik it is very unlikely that the roofbars from your previous motor will fit fully on your 75. This is because specific bars were designed for the 75 that fit into screw mountings on the roof. The 75 bars were manufactured by Thule and will definitely fit all Thule boxes and other items.
There is a set of 75 bars on ebay at the moment (link below) and if you go here there is a pic of a 75 with the bars fitted and a box on top (not a Thule one )