68 -69 some early 70's had X/894 heads. Most 70's and all 71's had J / U/ O/ Z heads they were all 915 with 202 valves . All 72 8.5-1 340s came with 915 heads with 188 valves. If you are running a full factory exhaust the 188's are all you need with 9-1 comp. Are 202's better? I asked my wife she said bigger is always better.
