Honestly, no offense to anybody here, but I wouldn't ask a question like this on anything but a building sciences forum, then I would simply ignore anybody who I couldn't vet as an expert, in the responses. As you are probably aware, your question is highly complex, and the variables are numerous, including everything from your location, to the smallest of original construction details. The materials and methods you choose can be wildly successful, or literally destroy the building. As a result the true experts in the building sciences field, like all good scientists, are constantly reviewing and challenging their ideas of best practice. Comments like, "well that didn't work as well as we hoped, so try this", or " this method is now generally accepted as a disaster in climate zones 5-8, but can preform well in southern zones" are common.
Incorrectly placed vapor barriers, spray foam, and/or high density cellulose installations have all successfully destroyed buildings. Doing so by creating conditions where brick exteriors spalled, cracked and eroded to the point that hundreds of years of wear occurred in the few years. The same products and techniques have caused mold growth and moisture damage in the walls of wood frame buildings to the point that demolition revealed severe cavity rot, mold and trapped moisture, rendering the building uninhabitable. They have also created conditions where wonderful old buildings no longer can keep a coat of paint on them, since the vapor dynamics have been altered, and wall cavity moisture in now migrating through the paint, and rotting the siding underneath. Sadly, the "cure" for this is often to hide the ongoing failure under vinyl siding. This is an logical as curing a lung infection with a nice new sweater. Oddly enough, the same techniques and material have been highly successful in other applications, other homes, other locations.
Currently, for the first time in my life, I'm doing battle with a sweet mid-century ranch we just bought. It is the first old home we ever bought, and in many ways it's an amazing place. Unfortunately, in the 1950s, there was no need to worry about heating costs, since oil was dirt cheap, so the place not only has no insulation in the walls, and no hope of putting any in. The place is built of block, with a brick exterior and furring strips and plasterboard nailed to the interior. Now if you live in Fl. or AZ. you might say, "what's the issue?" but this place is located 1000 miles north of there, on the east coast. While doing a lot of the same research the OP is doing, I found that best practice is to gut the interior, build stud walls an inch inside of the block, and spray at least R-10 closed cell foam on the block wall. Second choice, at a much lower cost, is to demo. Attach 2" of extruded poly to the walls, and stud frame the interior. Now there are two huge issues here. First, the interior of the home needs to be destroyed and rebuilt to accomplish this task. Second, the end result, according to a white paper from the DOE, is that I can look forward to a 9% reduction in heating costs. I about fell out of my chair when I read that figure, for two reasons. First, the savings are nearly negligible, and can be offset with things like a smart thermostat, and savvy buying of heating oil. Second, after destroying and rebuilding the interior of this home, my payback would probably work out to forty or fifty years, if ever. The fascinating part of the whole concept is that doing this type of retrofit to an existing brick building can, and has, destroyed many beautiful old brick structures. The reasons are complex, and basically boil down to. it would probably work fine given the specific details of my project, including location and condition of the structure. However, five hundred miles north, on the New England coast, with a building a century older, it may very well destroy the exterior in a few years, by compromising the ability of the exterior wall to full dry between rains, or snow, and leave saturated bricks to freeze and decompose.
In closing, I don't have an answer for you, I'm literally not smart enough, or well educated on the subject. Which you will find is a problem with 95% of those who you will deal with on the topic, ESPECIALLY insulation, remodeling, siding etc... contractors. I do know that there are many folks in you situation that have done energy audits, followed by comprehensive sealing and weather-tightening of the structure. The results can be shocking, and often result in a home that is totally comfortable, and much cheaper to heat, without going down the rabbit hole of, "will I totally F this home up by filling the walls with X,Y or Z, and who can I trust to give me the right answer to that question?"
As for specific recommendations, I would do the following, based on the assumption that you are keeping the majority of the exterior and interior wall surfaces intact. First, get an energy audit with a blower door test to see where the place is leaking. Next go gonzo on obsessively sealing everything and anything that leaks, doors, windows, electrical outlets, baseboard, rim joist, attic access, everything. Next, if needed, install quality triple track storms on every window, and good storm doors on every door. Finally, air seal and insulate the attic to the highest standards possible. In many cases this can result is savings of 50% and more on energy bills, and totally improve the "feel" of a drafty old place, which for a lot of folks makes the wall insulation problem go away. Good luck.