Had a 68 Chev with a 327 with over 90,000 miles on it that coughed up the carburetor and miss when revved up. Ran fine at idle. One of the exhaust lobes on the cam was bad. Had a used 283 cam laying around so I put that in it. Ran fine for many years after. It doesn't take that long to change the cam. If you do change the cam put new timing gears and timing chain on.
