Need help again

I have been dealing with my 350 sb for almost a month now and havent gotten anywhere. The problem started off as the car dieing at high rpm, now its practically dead. It idles rough, runs hot, powerless, and drops a lot of rpm and dies when given gas. I replaced the carb and still didnt solve my problem. I took it to the shop and they claimed it was the cam, i dont even think they looked at it, they told me it was a common problem in 305s. The cam in it was put in back in oct. I have also been told my timing could be terribly off. How can i set the timing? Do i need to pull the distributor out? I also stood by the exhaust while it was running and it was chop chop choppy. Very rough? Any help is and has been greatly appreciated. I really like my car but i have began to look for another import as my days with those were glorious-lol