No they never were made in 350RemMag - not the compacts or Frontiers.
My understanding is they came in 243, 7-08, 308. I'm not sure whether they made them in 260Rem or not - I think some were. But a very few were made in 300WSM and even fewer in 325WSM. A year ago Wes at Epps told me he sold one or two in 325WSM. I don't think the WSMs are chambered now at all. While I'm sure they work OK and reports indicate they shoot accurately, I believe the WSMs to be a bit impractical in a 16" tube - in strictly ballistic terms anyway.
For this year Ruger announced the target grey stainless Frontier version in 338Federal and 358Win. I think Ruger won't make many of these but that's uninformed conjecture on my part based on what I've seen in the past.
I believe the 358Win loses the least in that short tube and thererfore I prefer it. I snagged one (ordered it and waited 3months). My son shot it hunting without ear protection once and reported no ear trauma at all with the loads I developed. I tried it at dusk also to see if it was a serious flamethrower. Again with the load I have fashioned for the short barrel, there was no more flame than any other 22" tube rifle I have. The next best is the 338Fed in my opinion, then 308, and so on.
They are GREAT little hunters - I really like mine. You should get one.