I went through your same decision process on my Mustang. I am no paint expert, just a Mustang owner who wanted his car restored. The paint shops recommended the modern base/clear because it is easy to do, easy to repair, and looks better to most people, especially the casual observer. I was told that single stage is harder to do for a variety of reasons and may cost more because of the extra care and labor involved. Of course, you need to find someone who is an expert in this process and not someone just "willing" to do it for you. I spent a summer going to as many car shows and auctions as possible to look at cars and talk to owners about their paint and their opinions. My conclusion was that too many base/clear paint jobs look like the cars were dipped in clear. They would be more appropriate at a "Hot Rod" or custom show but not at all appropriate for a Concours restoration or one that tried to approach one. A very small percentage of the base/clear looked great, and to me, looked like single stage. I am sure that would not be the case for the judges at an MCA event though. My decision was to go with single stage urethane. The single stage paint just looked better to me and more appropriate for a 1960's car. It just "looks right." The paint shop picked BASF products and yes, they used BASF products for everything related to the job. They made that very clear that if there was a problem, the company would only stand by the warranty if all of their materials were used. They said they called the BASF Hot Line several times in the process to get technical advice and they were very happy with that help. The paint shop picked BASF, but I am sure there are other companies that make excellent products too. I am very happy with they paint job on the car and for a car that will be driven only several hundred miles a year this was the was to go.