Bought my First Mopar

Its a 273. I did a wet compression check and there was not change. Makes me think the bottom end might be OK. I'm not real familiar with Cams so I'm wondering if the cam he bought isn't right. The valve noise may indicate that I'm not opening my valves properly.
Is there a chance the last guy screwed up mechanical timing? If the chain is off a tooth can it run but with low compression?