Anyone have any experience with changing cams in crate?

great points t67.......ive mentioned i have the 391's..4speed..this is my first duster, so weight?....I know its alot lighter than my ebody..just by pushing it around....lol...its a full street car so lets say 3400lbs?.....carb I believe the gentleman that sold it to me said demon 750, .....like to run on pump gas, dizzy is what i believe came with the crate...which many guys had nothing good to say about them for whatever reason...told me to throw it away!,...get a mallory or msd. First Ive heard about that one?....Im using a mopar dizzy in my big block...I did send it to don at fbo to go over it..and so far its been excellent....again, when i get the car out...I'll get more specifics, timing, dizzy ect.....thanks again for the input guys I do appreciate the advice!