NG, I would match the cam [522/530] you mentioned above.Wouldn't worry about reversion as long as you have flappers installed on your exh tips.Match the 850 carb with 88primaries 94 secondaries on both.Some of the older boats didn't come with "J" tubes like the new 850 marine holleys,just make sure you'll have proper barbron flame arrestors.If you could trade your 850 in ,I would get a pair of new marine 850's .They're set by Holley and ready to bolt on and go. If you want ,call Dave monday through friday at 604-278 1880 for pricing in cdn dollar.I've seen some good prices at summit as well, but ask them for marine application for insurance purposes.