So I'm not clear on this. You think you have the right part and are concerned why it was engineered this way? Or you think you have the wrong part? If so, how does it compare to the original part?
If these parts are on a 65 Starfire they should be the same as a Delta, Dynamic or 98. A parts supplier can tell you what part their books say is correct for your car. But don't expect them to know why Oldsmobile spec'd these parts.
Inline Tube (
www.inlinetube.com) or someone similar may be able to explain why it was engineered this way. Personally I'd rather have 3/16" lines running the length of the car. Then the connections terminating with 1/8". Than have 1/8" the whole way.
Don