I had to modify the seat pan because the gas tank that was originally on my bike had big dents that are very hard to repair. I didn’t know about the damage, because someone filled the holes and repainted it. After removing the paint this was a big surprise. I bought a replacement gas tank on ebay. It had 1972 decals, but I was sure it is not a 1972 gas tank. When it was repainted I noticed the replacement tank is about 5 centimeters longer than my original tank!
Well, the replacement tank fits, but than there is no room for the seat. I relocated the seat 5 centimeters to the back and hopefully this will solve my problem. I will have the pan cleaned and powder coated and the seat will be recovered.