I would personally use the 450 on the Giraffe and take a 338 for the your other plains game. If you had to in a pinch you could try the 338 on the Giraffe but I personally found them to require quite a lot of killing(only have hunted one). Ask your PH about bullets on the Giraffe, mine wanted solids all the way, keep shooting as long as you can, he said. I am going to try a 2 gun safari next July in the Bubye for Buffalo, Giraffe and plains game. Stopping by Kowas safaris in Namibia for a double 5 day cull hunt on the way home. Taking 2 custom pre 64 Win's in 416 Rem and 338 Win Mag. You are right about one thing for sure, your overthinking it just like the rest of us, but that is half the fun. You could just take the old 375 and do it all.
Good luck and have a ball
