Oh, for heaven's sake, if that's your baby I suggest that you just leave it alone and find another bike/frame as a fixie project. You'll probably end up ruining the value of it anyway. Find the correct saddle and make it all original.

I used to have a Super Sport similar to yours but it was a darker brown. I heard that the frames are fillet-brazed chrome-moly. They are nice bikes and not turds.