Channel balance replacement
Sorry but I believe you are incorrect. If you inspect image I sent of the part needing replacement more closely, you will notice that, on each side, pointing upwards, are two rectangular plastic "ears", and between the ears is an indented area that fits around the retention clip for the lower end of the "block and tackle" on the end of the steel channel. I didn't see anything like the part I needed in the available images on your site; perhaps it is not available here.
I can offer a second opinion. I personally agree with the original recommendation. Those "ears" are basically just aligners, and I do not believe they contribute to the function of the shoe. Sometimes there are subtle differences between the same shoes from different brands. In this case, I am confident that your shoe is equivalent to one of the two shoes above.
I agree, there aren't any shoes on the market that match your exact style. It's very likely yours simply aren't made anymore. If you're convinced that neither our 15-004 or 15-005 will install on your metal channel, then you will probably need an all new balance like our Series 380 or Series 385.