I never trust the timing marks anymore. I haven't built near as many motors as a lot of other guys here on FABO but I have bought one gear set that was mis-marked. Ever since then I always use a degree wheel to make sure the cam is in sync with the crank.
On one other build we had a small block Chevy we couldn't get to run no matter what we tried. - It turned out that they had shipped my buddy a reverse grind camshaft (designed for some of the sprint car guys that spun their motors backwards).
Your cam timing may have been correct but unless you've verified it with a wheel it's not certain.
