OK so here's another options which basically uses placing the tape onto the receiver with the trunnion installed. If you are careful to lay your tape along the edge lines of the receiver, then mark the whole thing, it works well.
Lay the tape...
Mark the edge lines of the receiver and the groove line in the trunnion. (Pencil works well but I was too lazy to go get one)
I like to use a couple of pieces of sticky side up tape to put under the edge of the tape along the receiver to make little lift tabs. Silly in a way, but I think it helps.
Also it's important to secure the tape to the trunnion in two spots that give stability and counterbalance so that when you remove the trunnion you don't have too much shift.
Next you lift the tape from the receiver body, but not where it is secured to the trunnion. SLide the trunnion out, lay the tape back down, check the line you marked for the groove with the trunnion groove, and mark/punch holes in the tape.
Then slide the whole thing back together, lining up your marks.
Center punch your holes and commence drilling. I actually drill with the trunnion installed and through the tape. As above in the thread start with a small bit and drill the first hole. Check how close to center you are by looking at the well lit hole from the inside of the trunnion. You should be more than micro fractions of from center. If you are REALLY close then drill the last two holes and check them. Once you've got small holes that are close or centered, with the trunnion clamped into the receiver (so it doesn't push forward) you can usually drill with the right size bit for your rivets or walk up the size till you get there.
For the rear it really works the same way. For instance my PMKMS tape looked like this:
All the holes were drilled with the trunnion in place. Once the rivet holes are right, I'd recommend rivets the trunnion in place to allow you to work the folding stock holes to the right size. For the folder you can drill the holes in the receiver to the biggest you can get them, like the big hole you can actually drill all the way to a 1/2 bit. Then use your drill with diamond tip bits or brown grind stones to remove metal in the hole. Really easy.
EDIT: By the way by drilling with the trunnion in place it one helps to guide the bits and two using a drill press, once you drill your hole, you can drill straight through the hole in the trunnion and out the opposite side of the receiver, now both sides are drilled perfectly.