To make it easier to change the timing chain, back off all the rockers to lesseb the load on the lifters/cam....
As mentioned, changing the chain is not a big job, especially when you have it apart to the extent you have listed.
While you have it apart, suggest you pull the rear seal housing and swap out the barbell ...its in a port in rear of engine and seals off the oil flow out of the filter into the engine....
See this video on youtube
https://www.youtube.com/watch?v=4Hi9XMQ1S_4
Remember to clearance the oil pump when installing it....
