You will have a TOUGH time, finding, LEFT Handed, Tikka's in SOME, Cal's ! ( 6.5 Creed. ??,.. LOL !)
I'd choose the .243 win. for Varmints/ small Deer/ Antelope, etc. a PLEASANT Caliber, to shoot a LOT ! And the .270 WSM (or 7mm Rem Mag) for, EVERYTHING, else !There are many good Factory loads for the .270 WSM in 130, 140 and 150 grain loads, even 160 Partitions are available, Factory loaded. The 140 AccuBond, is amazingly,.. accurate, tough and FLAT shooting ! Unless, you are hunting, Alaskan Brown Bears at dangerously CLOSE Range, the .270 WSM / 7Rem Mag, WILL get the "Job",.. DONE ! Tikka's have, a very smooth Bolt and a LOWER "lift" than, most other Rifles and an adjustable Trigger that, rivals, a Timney for crispness ! There are many posts about, which Bullets to choose for the .243 online and only, a few DON'T, "work" in the 1-10 twist Bbl.! Good Luck,.. hope this, helps !
After you clarified I would agree with this. The recoil of a 300WM is nasty.