The 33 mouth piece may or may not work, depending on the width of the horse's tongue . The 33 is almost a high port bit.
I've never tried it, so can not give you first hand experience.
I just bought the shorter shanked version of the #33 and rode my mare in it. Yup, she loves it! Can't wait to try it on my Mustang.
I guess I was just curious if you guys had tried it since you have tried a few of the other Mylers. The Myler folks consider it a milder bit because of the tongue relief. It doesn't bother my mare's palate. She is very happy even when I engage stronger than ideal contact.
I've never liked riding in simple snaffles. But I've always had older horses and never HAD to use one. (That will all change when my colt comes home from the trainer. ) My guys have always done well in curb bits. I try to get short shanked versions. But I find most curb bits are interchangeable on my horses for some reason. They just do well in them. If I have any frustration with curb bits it's that they make the majority of them with long shanks. That's one of the reasons I'm attracted to the Mylers. You can get nice short shanked versions.