I thought the Lib Dems would share more with Labour than the SNP, given that the SNP is heavily right wing.
Nope. The SNP is to the left of all of the big three, though still only centre-left. There are in some rural areas so-called "Tory nationalist" voters, however, who are very conservative but vote SNP because they're also nationalist. Nationalist doesn't mean right-wing in this sense, it just means pro-independence.
In any case, a Labour-LD coalition wouldn't have a majority. 65 seats are needed for a majority, so the theoretically possible coalitions are (including only the minimal number of parties in each):
SNP-Lab
SNP-Con-LD
SNP-Con-Green
SNP-LD-Green
Lab-Con-LD
Lab-Con-Green
Lab-LD-Green-Margo MacDonald
Of those, only SNP-LD-Green is possible from an ideological standpoint. The Greens are as nationalist as the SNP, and Margo MacDonald is more nationalist than either. Since the LDs are big on consensus government, they're the only of the big three who could work with the nationalists. They might even allow a referendum on independence, knowing that it will be defeated. (Personally, I don't think the SNP is stupid enough to push for a referendum without a nationalist majority in the Parliament.)
I don't think either the SNP or Labour could run an effective minority government, both being so far short of a majority.