Looks interesting, but it also looks like adding a lot of complication to what doesn't need to complicated. Multiplexing works fine for cars with multiple loads and systems designed for them, but what need is there for mulitplexing on a 60s-70s car. You likely don't have power windows, power locks, low amperage switches, or a body module controlling lighting. The biggest advantage I see is that you could run a much smaller wire for loads like headlamps, but only from the switch to the control box. From the control box to the load it still needs the proper large gauge wire. There are plenty of available fuse/relay boxes on the market that will serve the same purpose with less hassle and lower price point. Take a look at what cooper bussman, littlefuse, and blue sea systems have available.
The prices listed are $1500 for that much money it needs to install itself in my car with all new wire and switches. I am going with one of these [ame]http://www1.cooperbussmann.com/pdf/36090f1a-b434-4910-98ec-1870f1f2519d.pdf[/ame] They are about $30 and you will spend another $30 on terminals and seals, but that is a huge price difference and there is no computer to fail or even confuse. Confused multiplexed automotive systems is becoming increasingly common. It is when systems lock up and will refuse to work until power has been disconnected and then when power is restored everything works fine again.
