There's definitely a lot to learn, especially if you're trying to cover the last 40 years. These RCs came from the factory with a bit a play by design and can tolerate a bit of wear without too much concern.

I dug out the old service manuals I have and there are definitely a bunch of differences over the years, but, luckily, it looks like it doesn't majorly affect a whole lot of compatibility between major wear parts, as long as you understand chassis you're working with. You're in the last generation of Super Dictator size.

I noticed there aren't any bearings in the counter gear, as the are where the bearing would have gone are replaced by the dampening mechanism. You're right about the 6x8 wheel bearing and the other nylon bushing being another oddity. I was working on my Traxxas Sledge and it too has two bearings in the front hub, so this is still the norm. To me, the strange part is the non standard sizes. There seems to be wide enough tolerance stacks to make standard size parts fit, i.e. the the bore of the knuckle being a little wide, the diameter of the spindle being a little under, and the sizing of the bearing always allowing for fit based on what pt# you order.

I've never considered chucking up 12mm bearing before, I've never even considered dissembling a bearing that small before to try, but if you can skim cut it for the satisfaction, the more power to ya, because at that point, lets be honest, you're just doing it for sheer desire vs necessity, law of diminishing results and all, I think you can still get the nylon for these to replace the worn pieces... Chucking up the axle to remove a mm may be feasible, and also using the dry ice method to press the bearings on so you can limit the amount of material you have to remove may be cool, I don't really understand how you're loosing wheel track by doing that though, I'm missing something there, just replacing the two nylon bushings with bearings, no?

There's definitely guys that have already designed adaptors for modern wheels and I've seen plenty of shock towers adapted for coil overs.

To be honest, the servo on these RCs are terrible no matter what, but you're not going to get away from that unless you go down the heavily modified route. The servo saver is going to introduce a lot of slop, also known as give in this case because these servos will not handle much, something will break on impact, likely to be your gear housing at a suspension mounting point. People say you can soak these old parts in some sort of hot silicone solution to "reinvigorate" them, I don't know, maybe... Boiling them does not work, I don't care what they say, that's not how ABS plastic works.

There's nothing out there for tie rods... There's TIG rod, get you some, UTP or tool steel TIG rod, I use it for more than just welding... Bend to the shape of your desire.

There is some truth to my original post though, a lot of those upgrades would probably work. Could use a cheaper servo though, and definitely use the Hobbywing 880, get a cheapo Hobbywing program card so you can set it up. I would just stick to NiMH batteries honestly, these aren't bashers. I've used a Gens Ace hard case 2S Lipo, and it's not much better, also, if you didn't know since you said you were just getting back into it, you can't run lipos down to 0, they catch on fire, new RCs have the controls for that, these do not... But NiMH with some modern properly wound 390 or even 380 would be fine.

Also, you sound pretty old school, and if you're as old as me, you have plenty of old school in you, but if you're wanting to get into this hobby, 3D printing is the way. turning down an axle vs enlarging a housing, as in enlarging the scale, is how the kids do it these days, that's how you can get off the shelf parts to work, you design around them. I 3D prototype and find solutions to problems I didn't know I had, just fixed my washing machine with a 3D part. I'm in Fusion at least 3 times a week... Having a 3D scanner is even better! If you already have this stuff you know, if you don't it sounds like you're a guy who also can't sit around and do nothing, so...