Reread, and did not see if there was a cam change. Also not aware that gen 1 engines use different length pushrods. My book says exhaust should have min .080, Intake .050 minimum clearance. It looks like the intake only is hitting, but not sure. Could you confirm? Is the engine still in the truck? Reason I ask, I would be checking the timing chain/gears. The 68 327 was the last year of production, and shares the same crank journals as the 350. Kinda a valuable engine, and as an ol' coggie, had lots of seat time in cars with 327's.