At one time I had a lot of 348 and 409 cars, hipo engines and speed parts. A blower manifold for a 409 is a rare item. The best I ever found was a 4-71 manifold, HOWEVER!.....

I did see an article where the top of a 2X4 manifold was milled flat, then had a flat plate, about an inch thick, bolted or welded on top of it for a 6-71.

I would suppose a bogus blower would keep cylinder pressures low enough for pump gas.