The Footsore Miniatures produce Goths that would be appropriate for Ostrogoths:
http://footsoreminiatures.co.uk/collections/28mm-goths-germanic
The Gripping Beast Rus would be wholly inappropriate.
Goths were essentially Early Saxons on horseback (Cavalry); the Goths and Saxons being a common people before their migrations in the early 1st Millennium. After their separations (at which point they were still somewhat unified by a similar language - capable of understanding the other) they went in separate directions.
The Rus would have some Gothic Influence, but they were a
much later peoples, and were mixed with a variety of others. The Goths turned eastward for a few Centuries, which is how they came to be predominantly on horseback, living in the Eastern European Steppe. while the Saxons turned westerly, and fought largely on foot (but never forgot their veneration of Horses, which they shared with the Goths and in which both languages reflect the centrality of the Horse to their mythologies).
Studying Tolkien's Middle-earth actually resulted in learning quite a lot about the relationships of the European "Barbarians," and to which groups have connections to whom.
Also, the East Riding Miniatures used to produce some Mounted Saxons that were perfect for Ostrogoths.
But, again... They are nearly impossible to discover nowadays.
Footsore offer quite a few mounted Saxons that would mix perfectly with their Goths, giving you an excellent mix of Ostrogothic types.
I have more than a few awaiting painting.
MB