I did my first plains game safari with a 7mm mag. Took everything from springbok to kudu without a problem. My hunting pard had the same with the same results. Your 7mm wsm will do the job with 160 Nosler Partitions or TSX's.
Don't buy another rifle, use that money for more trophy fees!!!!
Actually don't use the $$$ for more trophy fees
It cost a small fotune to export your trophies from Africa to the USA
Study dip, pack and ship fees for your region then remember there are fees inquired in the US to get said trophies to your door
This topic is rarely discussed
Go to the Accurate Reloading Africa forum and learn more on this before you go