Best way to weld in a fuel door

[1964C10]

This is a little ahead in my build but I got my fuel door from the pullityard today, came from a 93 chevy 1500. I just checked and the radius of the bed side is identical or at least when I laid it up against the inside of my fender it looked almost perfect. My question is now what is the best way to weld it in? as a rectangular/square patch panel or cut the fuel door right around the edge and then weld it it in where the door basically hits the bed side? The patch panel seems to me that it would be the hardest as far as not getting too much heat into the side. On the other hand, the other way you would have to make sure that it lined up perfectly so that the door doesn't sink or rise out of the bed side. Does my question make sense? No urgency on this, I just can't stop thinking about this truck