Any guidelines to how I check it for wear before I assemble my engine ?
Good question and quite difficult to answer without a new chain for comparison in overall length and sideways dangle. I have checked through some workshop manuals in English and German and other than x 96 links there is no mention of allowed tolerances.
All I can suggest is to accurately measure the distance between the 2 x pins on one link slack.
Now layout the chain and count the maximum number of straight links achievable on one side.
Multiply this number by the measurement taken from the 2 x pins on one link.
This is (possibly?) the theoretical length of what the straight links seen should be with no wear.
Now stretch the straight links and measure this actual length.
Using this actual length measurement against the theoretical length calculated, you should now be able to work out the percentage of wear.
Not sure where to go from here as my brain is now hurting, but greater than 10% I would probably change out. Although as a nice precautionary measure, I would be inclined to change it out regardless if you know the engine/chain mileage and it has done over 160k kms.
If anyone has a better idea please feel free to advise and I stand to be corrected.
NB: When previously in the car if the engine was lumpy on idle and you had erratic ignition timing this is a symptom of worn timing chain.