Always check the end gap. I just put a Wiseco piston in a kids RM80 and the end gap was too tight out of the box. The instruction sheet with the piston will give you the recommended end gap. A standard feeler guage will work fine for measureing. use a piston to square the rings in the bore.
I just use my fingers to squeeze the rings when I slide the jug on. Just take your time, you can feel if the rings aren't in the right place. And make sure you put them right side up. Many rings are marked as to which way they go. Read the instructions.
Well, I'd like to hear some other responses on torqueing. Myself, after 25 years of wrenching on bikes and everything else, I just have a feel for torque. I use the torque wrench on whatever I can and use my feel with a wrench, usually a nice long one on the ones I can't get a socket on.
Doesn't it feel good to do the work yourself. You'll learn so much more about your bike by doing your own work.
Lightfoot