Holy Cow! Where did you get an S-12 with so little mileage??? Looks great! Only bra I've seen besides mine.
Yes, mechanical lifters, if you adjust be careful to do it precisely. It would be better to live with some tick than to over adjust and burn some valves. Ticking won't hurt a thing, that's why you have a stereo. As I recall, Nissan recommends replacing the timing belt around 35k miles or so, good time to also adjust the valve lash. Get an old-school timing wheel to do it, or use a dial indicator.