.015" on Valve Cover Plate

[ray.rockwell@wg.com]

     Hello all,
     
     The plate on the valve cover of my 53TD specifies .015" for valve 
     settings. This is not the original engine (16330 engine SN) my late TD 
     came with. The cover looks like a TD cover.
     
     Any ideas what kind of car this came off of?
     
     I just purchased a new cam which has larger lobes. As an admitted 
     novice and therefore not trying to assume anything, how can I be sure 
     if I should be going the .019" or .012" route if there are such 
     routes? Is there something visible I can verify? I cannot read any 
     numbers off the old cam. Any other potential land mines I should watch 
     out for (tappets, pushrods, timing gears, valves, etc) before/while 
     installing the 'different looking' cam? 
     
     Thank in advance for any assistance!
     
     Ray Rockwell
     Cary, NC