The yield and tensile strengths of silicone bronze can be all over the map. A low silicone bronze like C65100 may have a yield strength of 15.2 ksi but a high silicone bronze such as C65500 with an H08 temper can have a yield strength as high as 61.9 ksi. Compared to 316L yield strength of 29.7 ksi you could either end up with a much stronger or much weaker chainplate.

You could contact Atlas Alloy http://www.atlasbronze.com/copper_alloys_product_sheet.html to see what shapes they have to offer. Also, National Bronze says they have rectangular bar C65500 http://www.nbmmetals.com/C65500-High-Silicon-Bronze-A-p/c65500.htm

Good luck.