4 door pans should fit the 2 door. I know on my '62 that a 4 door Belair is the same as a 2 door Impala. I sold the pans and firewall from the Belair to a friend that is using them in a convertible. He is like the resident expert when it comes to Chevies especially '62. Are you going to use the rockers also or just cut the pans out. If just cutting the pans..on the donor car...cut everything way bigger than what you need. First off, gut the car. Seats, glass, dash, everything that will come unbolted. You can either use some of this stuff later or resell it on Ebay. Pull the doors off. If you are going to use a cutting torch to cut the donor floor out, pull the body off the frame. This can be done with 4 people. Roll the car on it's side and cut from underneath. That way you can see what is going to be in the road. Like I said, cut everything much larger than you need and make sure you don't cut the braces. After removing the floor you can sell the car for the going scrap rate. BTW the 4 door frame should be the same as the 2 door frame so you have a spare you can clean up and paint. On the floor that is coming out of the 2 door you can (and is preferred) use a spotweld cutter. If you do not have access to one you can use a cutting torch. Cut everything smaller than what you need. You will also need good snips, preferrably electric shears, air chisel, and a good set of ear plugs. It is just a matter of cutting, trimmimg and fitting now. Take your time as it is not a very easy job to replace a floor. I done it in my '62 and it took a few weeks and everything still did not fit up right. I used aftermarket parts and had it in before I found the donor car. Factory parts fit much better. Before you weld in the new make sure you clean it of any undercoating, have it sandblasted, and ready to prime when you weld it back in. I think I covered most of the basics but if I didn't someone else will fill in what I missed. That's what's great about this board.
Kevin