Lifter preload and pushrod questions.

After can break in and road test, #7 cylinder died (popped out pushrod on exhaust. Cam doesn't look flat but valve are sticking open briefly before closing. Engine was built with all new parts and assembled by the same shop that did the machine work. Installation was by another shop that also converted the car from an auto to a stick. It's a 66 Barracuda, the header flange on drivers side covers the outer row of head bolts. Machine shop owner says sticky valves might have been caused by bad gas. Car has sat for about 6 years, but engine was built last fall (Aug 2009).