I don't have the technical background that these other guys have, but I do have driving experience. My 68 has the 327. I added the stock 4bbl intake and a late model Holley carb, rambler driver side exhaust manifold to get rear exit, and 2.5" dual exhaust. It also has a Pertronix kit in it. It's a big, heavy pickup that drives like one but it'll spin the 35s on dry pavement and haul a load of gravel without any issues
Zack - 68 J2000, AMC 327, 4bbl intake, dual exhaust, Pertronix upgrade, Holley 600cfm, T18, dana 20 (twin sticked), 3" body lift w/ 35x12.50 MTRs ~ running AND driving!