DIY cat tree base

[Kev.k]

I have a large holly tree that needs to come down. I want to use the trunk as a diy cat tree. 
 

I’m struggling with the base. It’s a relatively heavy trunk for indoor use and I want it to be sturdy.

 

I’m thinking of using a thick 3ft circular wooden base with 3 200mm bolts. 
 

Would really appreciate opinions and advice. 
 

Thanks, Kev