Did you keep the same timing chain that was on there with the wrong head?
i hope not, because i bought a truck a few years ago that had the same thing happen to it. The owner told me that the TC had broke and it had a rebuilt head on it so we tried to put a TC kit on it that i had and it wouldn't even come close to gettin up on the cam so we tried a old streched chain and still no go so we knew something was fishy because we saw a bunch of pry marks on the end of the head. then we finally pulled the motor and yanked the head and found the dome top head on the newer motor IDIOTS!

So thats why i hope you changed the chain because if you didn't i'll bet the chain is lose as hell because they really had to strech the hell out of that chain to get it on that head because the older heads are taller. makes me wonder how well that truck ran before the TC broke, way oversized combustion chamber so no power, and it was on 33's with stock gears....
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