I have converted two Magnum intake manifold to 4bbl but have yet to try one out. A few people have and it seems the best results are from the Edelbrock 500 cfm manifold, the 600cfm may be a bit much but hopefully someone else that's done one can share their experience. The 292 Pertronix will work as long as you have the same smaller distributor but I recommend an HEI for reliability and ease of the availability of parts as well as overall increase in performance.
