That looks like a well-engineered installation. The rear exit manifolds for a 305 engine like I posted would be the obvious choice, if you can source parts from a donor vehicle from the early 1980s. Mid-sized Chevy, Pontiac, and some Oldsmobile vehicles all ran the small block Chevy V8.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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