From what I researched, the Edelbrock R4B is more-or-less equivalent to a stock 4-bbl intake, which isn't a bad intake. It was an AMC option in the 1970s. But they aren't being made anymore, and thus are expensive when you find one; usually priced more than buying a new Performer or Air-Gap. For an engine that won't see more than 4000 RPM, you might actually look for a SP2P; this is a horrible, little, tiny intake that falls flat at high RPM, but might be just the ticket for your build. Because they are so universally despised, they are cheap (even free?) when found. For going truly cheap and stock, just pick up any 4-bbl cast-iron intake and call it a day.
The 291c heads are like finding hen's teeth, and are HIGHLY desired by the drag-racers since they're an OEM high-compression head and allows them to compete in whatever stock-class (using stock heads) that AMCs clean up in. I've never seen 291c heads in real life, and have only seen pictures of the casting numbers on the Internet. That being said, the stock 360/401 heads (they are the same casting) flow nicely.
The bigger question is: are you really wanting to stick with all stock and junkyard components, or are you willing to go aftermarket? 4000 RPM is a slooooow motor. Stock redline for the AMC V8s is 5000 RPM, and my built 401 has no problem touching the artificial rev-limiter I have set at 5500. But I also have a ton of mods into the motor, including the internal oil line (which is still probably overkill for what I do). For a truly stock build, you don't need to sweat any of the special mods.
A DUI distributor is itself aftermarket, and thus not cheap. It's a great system, but you can also run the stock electronic ignition, with the Nutter bypass, the TFI cap upgrade, and an aftermarket HEI-style coil, and have a great/cheap system.
The stock carb is the Motorcraft 4350. Not a bad little carb. Rebuild it and call it a day.
As for exhaust manifolds, there were essentially two styles: the "log" and the "free-flow." Pre-1980 Jeeps came with the "free-flow" and are great manifolds in stock configuration, while the left side log-style showed up in FSJs post-1980, and you'll find the right-side log-style in some of the '70s AMC cars. There was enough demand for the free-flow manifolds that the aftermarket actually started reproducing them, and there are also some great header options out there too with Thorley and Edelbrock.
As for cams, the Edelbrock Performer is a great little cam. It does more to wake up a 304 than a 360, but you'd probably be happy with it. The FSJ guys also swear by the Summit 8600. I've run the 8601 and was happy with it, but kept killing lifters (although in retrospect, I think it was unrelated to the cam).
