used om603 out of car known runner what should I do

[12MPGHWY]

So I have a used 1987 om603 engine out of the car, number 15 or 16 head (can't remeber off hand but not 14). I drove the car around before the engine was pulled it ran great, idled good etc.

So while I have it out, I want to go through and look for things that may turn into issues with time.

Was planning to do the head gasket, timing chain and take a look at the main bearings.

Is there anything else I should do?

Also is the ATE head gasket kit any good they have one at my local napa for 150 dollars?

Thanks

usage is unknown odometer stoped at just 80K miles