VW, DUAL PORT, STROKER 78 X 92, CROSS FIRE INTAKE

[hotrodsurplus]

Your idea is sound as this manifold better suits the VW firing order; however, the 24mm venturis in a Zenith are way too small for that engine with that manifold. Just swapping in a simple plenum manifold would unlock at least another 20hp if only because each cylinder would benefit from the flow provided by both venturis and not just one. Two 24mm venturis have 900mm surface area, or roughly the area of a single choke in a 34mm in a 40mm Weber or Dellorto. Try it out if you haven't already.

[mindfuckerification]

wht cam and heads? only 75 hp out of a stroker? seems low