Thanks Bill. Your arrangement is similar to what I did for a well worn 235 engine with original draft tube.
I was a kid in high school and couldn't afford an engine rebuild.
It cut down on the burning oil smell inside the cab.
Unfortunately it didn't help the driver's behind me at the stoplight...big grin.

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."