Hey, I have an optimum lig for my alto, I like it. Its not bright gold colored, if you happen to have seen a reference alto its a little lighter than that. Kind of a dark gold. The francois lig I don't have, but I've heard lots of good comments about it. You can also get it silver plated (Bright) or gold plated (dark) from this website. But I see theres no option for metal tenor mouthpieces for optimum...I'm thinking that you should order a regular alto mouthpiece, you could try comparing the size of your Link to one of your friends alto plastic mouthpieces (like selmer) to see if they're similar. If you find the ligature on this website you can ask a question about it what size you should get for otto link, but it will take a few days till he responds.

im skeptical you'll find an optimum for a link. the link has that ridge on the top and it would make it not be able to fir right. it would work, but no gurantees on how well. i play on a francois louis on both alto and bari, but only for legit. they arent jazzy enought for me, try an olege, they work very well on metal. and if you get a francois luis, you will probably have to bend it to fit.