The key is to match the parts with what you have to work with . All to often people want to use too much cam for the motor they have,also they think bigger is better when they are talking carburators.Your motor may be faster if you know where a half mile track is ,but you're talking 1/8th mile. You took all the bottom end power out of your motor.Bigger valves,bigger cam , bigger carb.Want to slow it down even more,put large tube headers and bigger exaust on it. That should cost you a couple more tenths.Sounds like Im trying to give You a hard time , I'm not ! You Can have a real good running 283,something you'l really be pleased with. Call Comp Cams Help line1-800 -9990853.Tell them what you have,what you want to do with it and see what they reccomend.Good Luck!