Cloyes double roller after 1K

That IS a lot of slack for 1000 miles....I would expect 3, maybe 4, degrees of cam retard with that much slack. (Yes I have made measurements on that before...) The tensioner does not fix that as noted before. That amount of retard is definitely gonna show up in the low- and mid-RPM ranges.

At least move the multi-keyway timing sprocket to correct that.. but I'd replace that chain if the engine is of any value and get the cam timing back to where it should be.