Help me turn Aethon Shaan into Tyberos The Red Wake!

Hello there! I am a very enthusiastic Carcharodons fan and have chosen to play them as their (most likely) gensire, the Raven Guard.

However I am stuck, I've kitbashed a lot of my models to look more sharky, and even got a Tyberos custom model, but he is HUGE (about the same size as the lion).

I really want to run Tyberos in my army but I can't find a way around putting a terminator on Aethon's stump (which would look very silly).

Any advice would be wonderful, thank you!