When I look at your pictures......that could be my house., right down to the brick colour (mine was built in '58). If you look at the outside and see every fifth or sixth brick installed crossways you know you have a solid masonary wall. That brick ties in the blocks next to the bricks. If you have a brick garage too you'll see the other end of that brick in the (inside) concrete block wall. Solid masonary was standard untill the sixties, when they switched to 2 X 4 framework with a brick veneer on the outside.
We left that insulated house behind thity years ago, but here's what we did. All the outside walls were insulated, flat steel studs were secured to the walls rigidly holding the insulation boards on., drywall was screwed to those studs. Long screws and inserts held the studs on. And yes it was a big job.
The studs....
Make your walls stable using this Bailey metal wind bracing. Its heavy-duty steel core makes it durable. The WB-747, flat metal brace has a flush top...
www.rona.ca
You have three choices. Insulate inside, insulate outside (and stucco over it) or leave it as is.
Just went outside to take a picture of my crossways bricks.