Ditto on keeping the carb and headers. They will work fine for the time being. A MP distributor with the proper timing curve will work just fine also. I built a 10 to 1 496 for my buddies challenger that runs very well with out of the box parts. I used a set of OOTB RPM eddy heads, small 260 @.050 solid roller cam, comp pro magnum 1.5 rockers, Holley SD intake and 1050 annular 4150 series carb. The engine is about as docile as can be and makes goobs of power from off idle to 6500 rpm. You might consider the Holley SD intake also over the RPM for more hood clearance too in your application.