timing chain making noise....help?

Hi guys... i finished my motor swap project... it runs!!!! Well!!!! However the new engine has 35xxx miles... and has a slightly ticky timing chain, clean on accel... but idling and when decelling... for this reason i was assuming it wasnt the valves...

The one that came out... with a blown cylinder had only 20xxx....

So the question is... can i just get a manual cam chain tensioner? Retension the stock one?
Or should i just go and do a whole new chain... pulling the motor again would suck but its easy enough..

Also- if i pull out the chain from the 20xxx blown engine and it doesnt look ruined from the metal everywhere else in engine... can i slap that in? Would probably be best to just get a new one... ?

Also if it helps i can video the noise

Thanks in advance for any help or advice given...

I will eventually do a whole write up on the engine swap....