Would these work with Suntour BL components? They are rated for 10/12spd. I also have a set of vintage suntour XC thumb shifters and I'm wondering if they could be configured to work with my existing drivetrain.
those shifters in your picture look like friction, so they should work with anything. ditto the suntour thumbies.
I've run friction with newer 8 speed HG cassettes, and found that the rear shifting was a little twitchy, the HG cassettes really wanna grab the chain and move it to the next gear, so finding the sweet spot is a little harder than it was with old school 5-6 speed freewheels where the teeth were straight.
SunTour "Blue Line" components date from the period of six or seven cog clusters and should work fine with those SunTour Bar-Con shifters. If you intend to use more cogs in the rear you may find that a deft touch is needed to prevent overshifting. The XC thumb shifters should also work fine with the Blue Line derailleurs, with the same caveat.