"Quadifying" a twin can be done, many quad experiments work like that and usually with smaller fins in front. But the Starboard Quads are a bit different and if you wanna go by the fin setup on the Quad 71 (the closest to the EVO 75) it will not work. ON that board the rear fins are only 105mm apart (c-c) which is to close for a twin. The center of the rear fins are 183mm fromt he tail and the center of the front boxes 340mm from the tail, exactly level with the rear option of the back strap front screw (a good guideline for the front fin center, I think). The (back of the) front fins are 47mm from the rail (the actual rail, not the tucked under line).
If you start with twinsers, maybe you can put them 130mm apart and then not too far forwards (say with the front right under the front plug for the back strap, not further forwards). Then you could probably quadify it later and runt the rear fins right at the back of the boxes.