One problem my current limiting scheme was going to give me was if one LED failed open circuit, the increased current through the remaining circuit would possibly desroy those LEDs. So, I redesigned it a bit:
This will let me toggle between 350 mA and 750 mA, and if one LED fails open circuit, the current through the other leg will be limited to less than 1000mA, which shouldn't burn them out.
Today I got the power supply, and it looks very good. And, I got the "heat sink" assembled, but my wife has my camera so I can't get a pic of it yet. I still need to flatten the mounting surfaces a bit and polish it some.
While working on it I decided that "heat sink" isn't the right name for this. It is a heat exchanger, not a heat sink. A heat sink stores heat, but this is supposed to transfer the heat to the air flow going by it. Thinking of it that way makes the design make a lot more sense to me. Spent another $2.24 on nuts and bolts today. Cost is now $30.