MCB,
GunFunds and wives always an issue

Dollar for Dollar .375 H&H,.416 Rigby, .458Win, CZ $600 to 900 used.(BTW, Have owned them all)

Used Chapuis UGEX 9.3x74 about $5000

Used (plain ) Krieghoff .470 $10 to 12K (Did see one sell for $8500 recently)(I had the K in 500NE)

Pre - 64 Mod 70 .375 H&H $4000 to $7000 (condition,condition,condition)

Or what ever you want-----

Can't go wrong with any of your mentioned choices.
But a good first safari with your .270 and a .375 sounds pretty good.