Any of those would work.
More power is better IF you can handle it as well as a lighter gun. The 500 has too much recovery time to suit me.

I have been really happy with my 450 No2

Since lion is on the menu I would want a scope fitted in QD [claw] mounts.
Lion is probably the hardest trophy to "get".
If only taking one rifle [something I would NEVER do], I would take my 450/400 3 1/4" double fitted with a S&B 1.1-4, with its illuminated reticle, in claw mounts.