Anyone have any experience with changing cams in crate?

ya know....its a driver...dont race it.....it starts, goes, ect....doesnt really have any problems per say.......maybe could you a lil timing gun on it....does have a lil dieseling goin on some times after shut off....thought maybe its the shitty gas we have, a lil race fuel seems to help it...really havent owned it long, but might throw a gun on it and see....any suggestions on a initial and total? for that set up