The house is already built (1944). The cinderblock basement walls were new (1995 when the new highway forced a move to the back of the property).
We did NOT insulate or fill the cinderblock walls at the time. I do NOT want to cover/insulate inside the basement or outside the basement for a lot of reasons -- expense and bother moving electric, plumbing, washer, dryer, hot water heater, bathtub, interior walls and stairs, or landscaping, etc.
Is there a product to put INSIDE the concrete block walls? There is a 2-by wood face plate on top of the block that could be drilled (with the right tool) and something appropriate could be akwardly poured/sprayed inside the blocks for insulation.
If you are just looking to insulate, there is a product that resembles Styrofoam balls (it may be styrofoam). I've ran acrossed it several times on renovation jobs when I had to drill through the wall. It pours out all over when you drill into the hollow cavity.
I'm not sure of the actual name or where you can get it.
The little round balls is most likely perlite. From what I can determine, filling the cavities with perlite increases the r-value from a little less that 3 to around 9 on lightwieght block walls and from 2 to 4 on heavyweight block walls. Whether that is enough of a gain for the bother is for you to decide. Remember you are going to have to drill a hole every 8 INCHES through the sill plate and then plug it back up.
If it was me I'd re-evaluate putting rigid foam board on the inside of the walls even if I had to skip the places were the wood from interior walls and the stairwell is against the concrete. The wood itself provides more insulation that the whole thickness of the concrete wall. How big a pain moving the wiring and plumbing out an inch or two is going to will depend on how it's mounted. I wouldn't cover either up because I fear that the plumbing would freeze being on the wrong side of the insulation and the wire would over heat being covered up with insulation.