You can replace them with more modern fittings and run new brake lines. I'm guessing that you want it to be original and "correct" so Mark is probably your best bet. Those fittings are nearly impossible to find.
As has been stated prep is the key. Prep is very difficult. Even morso if it's a DIY situation.
The inherent problem with liner products is that they have much more structure (so to speak) than primer and paint coatings. If there is a place on the body with less than perfect surface prep the...
My cabin is near Minocqua but I live in Madison like you do. Minocqua is pretty far from Hiawatha which looks awesome but I've never visited. Probably at least a 4 hour drive from Minocqua and at least 6.5 from Madison.
There are tons of forest service roads in various states of disrepair in...
Diesel oil. Zddp additive. 5000 miles. Or 3000 miles. It's a 2F. Sure, they need oil , but they can power forklifts on fermented sea water. You could put rendered pork fat that had been used for three batches of carnitas in the crankcase and as long as you don't live in Flin Flan you're probably...
Maybe, but probably not. That thing just restricts in one direction to delay the choke breaker. If you put it in the other way it just overcomes the choke sooner. Only a problem if it's cold out and even then not a big deal. One can eliminate it and have a good tune anyway.
Carefully, after drilling the hole and (ideally) using a sized ream to make the hole the proper size. Or just the right drill bit. And oil. And being extra careful. Or maybe with a vice grip. But, again, carefully.
Generally those are drilled, tapped and closed with an appropriate threaded plug.
Edit: I would worry about an expansion plug coming out due to heat cycling.
Overall, that thing looks great. Brazing is awesome. Brass doesn't rust. Other than the rear sill, it doesn't look like it needs much replaced. Just a bunch of hammer and dolly planishing.
That's a cool video.
And I should have said, I'm not aware of a machinist doing THESE manifolds that way. I think the problem with that (and as a side note, it's also a problem with the fly cutter) is that because you have two different materials (softish aluminum and much harder cast ferrous...