The .357Max will be stretched at 150 yards compared to the 6.5s. A lot will depend on which hangun you prefer, the Contender or the Encore. I would not get a .357Max in an Encore - too big and heavy for such a small cartridge, and the Maxi can be loaded as hot as practical in the Contender anyway. If you want an Encore, then the 6.5s are the better choice.
I have used the .260 Remington in rifles, and it performs great. I prefer it over the 6.5x55 particularly if factory ammo will be used. Handloaded, both will perform the same. Since you already own a Swede it may be a good choice.