I had the same problem when I mounted my Magnum 70 RFS on my Tower 60 trainer. I cut out an opening to alow for the needle valve. The only proplem is when I put the plane in last year, the impact shoved the fire wall back and breaking off the needle valve in the nice little opening I cut for it. $45.00 for a new carb. With the way your engine is being mounted maybe this is less like to happen, just food for thought.