The 128 intake is for RB with Stage VI heads so it is a super wide intake manifold. For a RB block with original (or reproduction) Max Wedge heads you need the 337 intake.

As far as I know the 337 intakes are in stock. They run about $200 which is a great deal. They are a low profile intake and might just fit under a stock hood depending on what air cleaner you use.

I don't know why Mopar Performance hasn't done a little better job promoting this intake. It is the only one that fits this application and it really works pretty well. Nobody else makes a single 4bbl intake that works with the original MW heads on a stock block. (The Indy intakes would work if someone tooled up a bathtub intake manifold gasket that had MW port sizes but nobody has ever done that either)

Kind of wild that after 40 years of development there are still parts that nobody has ever tooled up.