Hey all. More info to share on a disc brake conversion for our 600s. I have learned that, while the calipers for a 124 and X1/9 appear to be the same, the caliper brackets are different. It doesnt matter which you use, I dont think, but it does matter that you get the correct hardware for your caliper bracket. Here is a pic of two caliper brackets...
I believe that 124 bracket is on the left, and the X1/9 bracket is on the right. It makes sense folks mix them up. The important thing to note are the caliper bias springs (installed in the pic). The X1/9 brackets take a spring with a bend at the caliper. Also, the mounting holes are in very different locations. See here:
the kit i ordered above (oldtimer shop) came with X1/9 brackets, but no hardware. So, it took a while for me to figure out the correct springs. I hope this saves someone the time.
Here is how my setup finally turned out:
I did have to file the wedges and caliper bracket to get my caliper to slide smoothly. Without some filing, it would bind and not release the pad on one side. I sure hope they work well enough to be worth the hassle.