Now for a little heresy! I love working with metal and I am a fair welder...but in many cases there is a different option. FIBERGLASS. I know, I know, real steel or NO deal. When I used glass on my 1935 Ford pickup back in 1969/70, panels were not available like today, plus I was young and did not understand the error of my ways. Knowing there was enough floor left for a good pattern, I used a 36 grit disc and cut out all rust, mixed up fiberglass matt and started putting it over the roughed metal. Using filler with strands of glass and cardboard backing, I made new floors. With a little body work to smooth things out, flat black paint then using what I think was the forerunner of pickup bed spray liner, I had a very good floor. Underneath I smoothed it a little and sprayed undercoating as it was a driver. Two years later I traded it for a 1940 Ford coupe then 30 years later about 2000, I got to see it again. The floors were still nice. Just like welding, how one does the work makes all the difference. I LOVE steel, but some guys don't have a welder or the bucks to have it done, but $50.00/$100.00 of glass and undercoating can get things done.