"Perhaps have someone who's used to "old brakes" (manual master cyl, drum's all around) give it a drive for an eval??
`had a 68 ford ranch wagon, which I believe was manual with drum all around and while a heavy car I don't recall them as being "poor" brakes."
Sorry you had so much trouble with the wheels - seems like that should be standard info. The skinny tires will work well on these old jeeps and help the old F134 feel a bit peppier and keep the steering a bit more functional. I wish I could run 33x9.5 - hard to find these days. As you say, its probably time to just drive it as is for a while and see how its doing.
If the willys is still running the OEM style 9" brakes - there is nothing that can be done to make them feel good. At best you can make them feel like they 'kinda' work. Mostly they just don't work. The 9" brakes were not really functional on the original MBs and CJ2As - you m170 is quite a bit heavier. The 10" bendix style brakes from 66-71 (with v6 only) are adequate for stock tires and up to 30 or 31". Its bolt on and there is a set for sale on FoCo CL. That is what I ran for quite a lot of years on my cj5. They certainly don't feel great - but the bendix design allows for quite a bit of stopping power if you press really hard (its probably the best non-power design drum brake you can get). If you can push the pedal hard enough, they will work better. I finally upgraded to 11" bendix drums after trying to make the 10" work with my 33s. WAY BETTER! I only did the front drum and its still is WAY BETTER. 11" bendix drums were used on ford trucks of the era quite nicely (maybe even the 68 ford ranch wagon). Disc brakes will help with wet and mud - but as there is no power assist, the 11" drums are equal in dry conditions (I had manual front discs on my previous cj). The bendix also automatically adjust when you drive in reverse and apply the brakes...sometimes I just go forward and back a few times with hard stops to get them adjusted. Can't remember how the 9" adjust off hand - will check the manual.
Another thing - the jeep owners manual doesn't call it an emergency brake. It very specifically states its a parking brake (seriously - this is long referenced issue with jeep that actually ended up in some legal court case at some point). Its a driveline mounted 9" drum - even when brand new and in full working condition it will not stop a moving vehicle (4 of them barely stop a jeep). Don't worry, after a few weeks the leaking D18 will ooze oil onto the drum and then it won't work as a parking brake either. But, there is an adjuster screw inside the brake drum that will help.
Its a 1955 jeep - which is old - but its build on technology from the 1940s! Think of what a computer from 80 years ago is capable of.....
I like driving my jeep more than wrenching - really I do! But I spend more time wrenching than I like cause most shops can't do anything better with it than I can do and they charge a ton. I don't know anything about fixing vehicles - but anyone can fix old jeeps with 1/2" wrench and a bunch of degreaser. And stuff breaks all the time...and its hard to get parts for...and when you do find parts, its OMIX-ADA junk. The 71 cj5 you ran with the other day had its issues as well - there is a reason old iron groups exist. You gotta like the old iron as much as the wheeling sometimes. Any day it returns to the house under its own power is a good day...and every once in a while it will surprise everyone with what this old iron is capable of. I'd love to build an old jeep up to a reliable modern wheeler - figuring over 10k if I do the work...20k+ if a shop does it. And of course, whatever you expect the bill to be...double it.