Help gts125 into vx125 frame

My vx 125 lump seized on me so got my hands on a Vespa gts 125 lump, swapped wheel hub over with mine snug fit and exhaust bracket bolted up lovely, lump straight in too frame like a glove, plugged everything in and bike fired up after a few second once petrol got threw, went to sit on bike and frame at front of seat is hitting on the cam casing, I mean and inche clearance when on stand I sit on it and bang bang bang.. HELP!! What do I do?? Got so far and don't want to turn back now.,

 

Could it be to do with the stand?