overdue timing chain - any last words

[old blue]

I am taking my 85 500 SEL with 109k to get the chain replaced along with the guides. I have searched this remarkable site and read every possible thread on the subject ((Something everyone should do before firing off a question)). So I know I am on borrowed time. Other than occasional rough idle (chain slack/O2 sensor?) the car is a dream!

Unfortunately I am moving shortly, and will be leaving my trusted independent mechanic behind. So I am having him go over the car and prioritize "anticipated" future needs.

My question is:
What about after the replacement? Are there things I should look for. Should I do an oil change shortly thereafter? In the past, solving one problem may have highlighted another, which was then taken care of. In this case I do not have that luxury. If replacing the chain and the O2 sensor do not solve the idle problem then where would you look next - fuel delivery, injection?

Danke