Smokey,
You are correct that the M48 Yugo Mauser 98 actions can be rebarrelled for the .358 Winchester cartridge. It's relatively easy to do. The cartridge head diameter is same for 7.92x57 Mauser, .308, and .358 Winchester. a .308 Winchester conversion would need little if any magazine work to feed smoothly.
A new barrel needs to be fitted and headspaced of course.
And possibly cartridge stops installed to prevent the cartridges in the box magazine from recoiling and damaging the bullet tips. I like to use pieces cut from large cotter pins and silver soldered to the walls of the magazine. They should be position just forward of the cartridge shoulders when the cartridges are in the rearmost position in the box.
That's all!