Finding left-handed rifles in a specific caliber / material combination can be tough sometimes. I have never shot a Shaw Custom rifle but I just wanted you to be aware of their existence if you weren't.
https://www.shawcustombarrels.com/mk-vii/Basically Shaw takes their custom barrels & builds a rifle using a Savage receiver. So you can specify right / left or chrome moly / stainless in a wide selection of calibers. I clicked a few options and built a left-handed 416 Ruger in stainless with a laminated stock for less than $1,200. Based on your specified criteria of wanting a big caliber to shoot a bear at 5 yards, I thought this might be an adequate option worth considering.