If you have to do that may as well do plenum, rest of tune-up stuff, new o2 sensors, possible cat and a good double roller timing chain. Gonna be there so might as well, save the job of taking it apart multiple times. You're gonna have to anyways down the road now if you don't.

 

Tensioner doesn't compensate for a stretched chain, it just stabilizes the timing as the chain stretches, instead of letting it bounce around by however much slop is in the system. The chain is still stretched, and timing will still be off..... but, with the double roller chain, it will only really stretch a degree or three.