i happen to work with a bunch of guys who worked for chrsyler here in kenosha wi, 1970 heads t/a and aar cuda had offset pushrods and rockersthe 69, 70 ,71 heads had adjustable rockers on shaft available either way.
Sounds like a broken rocker arm if its adjustable type check all the tips,could just be misadjustment whats the valve lash set at??..unless it's non adjustable valvetrain..