Ticking from engine.........vari's with rpm's

I have a 68 w/ a 302 that i bought recently from a guy that thought it was completly dead and needed to be junked. All it needed was a new battery and alternator. After getting it running again i noticed there is a ticking noise coming from the passenger valve cover area. I can seem to isolate it anywhere specific though. I have re-tightened everything to specs in the book and still its there. I even put up a drop sheet and ran the engine with the cover off hoping to isolate the sound better. Nothing but a mild mess. Im nothing more than a weekend grease monkey thats still learning, the only idea i have left is maybe a small exaust leak around the header gasket but if it is i cant seem to find it. Any help from you guys with more experience would be very appreciated. thanks.......mac

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66,289,coupe,MT-3
68,302,coupe,AT
Gotta love the true american car.....