Did my 66 last year. Like many have said, the DSE kit is alot less work, looks great in the end but costs a pretty penny. I split my factory tub and sectioned in a strip of sheet metal. I'm an ok welder and it turned out to be a PITA because the factory tub is pretty thin gauge and I blew through quite a bit. Also had to run seam sealer across every lap weld.
You could butt weld in a section of sheet metal but I felt that would be even more work, so I lap welded. I'm not going to enter any shows and I will drive this car so I'm ok with the way the tubs turned out.
It depends on what your end goal is and how much your willing to spend. DSE kit is great but pricey, DIY cheap but alot of work.