How much did you spend? If you didn't spend "around" or over 100 bucks, you bought junk. Yes, IMO even on a stone stock engine you need a good quality chain set. IMO it's that important. What you get with a more expensive chain are bigger rollers, solid rollers and not the old split rollers. The 100 dollar plus sets are billet steel. I would not build even a stock engine now with less. Camshaft timing is as crucial to a good running stock engine as it is to a high performance build. This is why performance drops off some in a new build using lesser quality chain sets. Not saying you do this just making a statement.....if you always let price dictate your parts purchases, you will always come out with something inferior to what it could have been. And remember, the "about 100 buck" chain sets are not the most expensive. They are middle of the road. There are more expensive sets all the way up to belt drives, but in general the 100 dollar mark or "there about" is a good indicator you got a good set.
Now, as to the excessive play.....and it is excessive. The book spec is 1/2" play maximum before needing to be replaced. That's for a stock engine, not one that you want to have performance out of for any reasonable length of time and certainly not for a brand new one. While using a tensioner is ok, all that does is remove the slop. It does nothing to correct camshaft timing from a loose chain.
