Neck collar fit

I have a pair of antique, studded, ox collars with nice mellow tone bells which were given to me. They fit my oxen necks up near the top but are too small when I slide them down the neck. It’s possible to lengthen the strap end which is on the inside of the collars and would not show in the yoke. Before I did that I wondered about fitting leather collars to ox necks. Is it ok to have them ride up near the top or should they be big enough to fit all the way down the neck. These are strictly for dress up occasions and not for everyday use.