Thank you everyone for the positive replies without any nitpicking. We are very happy about the puppy and he is something I've wanted for a while now. He is an absolute joy and has made me do a lot of smiling the past few days.

A few names I really like...
Mufasa, of course. It has always been "my" name for my next male dog, to carry on TLK theme in honor of Simba. I have already started calling him Moo for short.

Kovu - I love "K" names and it would fit nicely with Kiara. Koko for a nickname.
I also really like Pumbaa but I think it's too close to Simba. His chubby belly did remind me of that, though.

I also really like Frank Sinatra so I thought of naming him that as his full name and calling him Frankie or Frank for short. But then I thought of Beenie and Frankie and I wouldn't want to take their names.

Scar from TLK is another name I thought of. Short and manly.

Nuka is another TLK name and can be male or female. It means younger siblings in Greenlandic so it really works.