You might have a conversation with Tom Langdon (listed under the "12-Port Advertisers" link). He is familiar with your setup and i think that he could help make up a linkage that would meet your needs. On Tom's website you can see pictures of (his brother-in-law) Elmer Stange's Dodge pickup with a Chrysler flathead and truck dual manifold.

God's Peace to you.

d
Inliner #1450