Are all slant dip sticks the same length?Where to get one?

2 bbl manifolds are probably an ebay item, unless your junkyards are better. I very rarely see 1980 & earlier Dodge around here, though trucks still show up. The carb is a fairly common Carter BBD, which were also used on 318 V-8's, though there might be a particular PN that is better for slants. You might have better luck finding a 4 bbl aluminum intake (Offenhauser, Clifford). I eventually got one off ebay. You would want the smallest 4 bbl carburetor you can find (390 cfm) or maybe consider throttle body EFI, like FI Tech (~$700). You also need special kick-down linkage and such for the Super-Six setup.