How to live with an M156....
 

It's a high performance engine, basically a Hemi with 4 valves per cylinder and high compression. The early production engines have noisy valve "buckets", cam wear issues and head bolts that just aren't able to endure sustained performance driving.

So, what are we in for trying to get this wonderful beast to 100,000 or more miles? Having the service bulletins done, oil changes of course, avoiding incomplete thermal cycles (a cold start and shut off before getting up to op. temp.) The head bolts on early engines should probably be changed out for the new design or ARP studs. Do these things and this engine will bring you a lot of smiles.

What else do we need to factor in?

Drive it.

My oil analysis has been spotless since 80K. Now at 134K.

I do have the dreaded intake manifold leak. Need to fix.

Intake leak....is this common?

What is involved in the fix? There is a carbon fibre aftermarket replacement. Yeah, spendy if you go that way.

It's just the intake gasket, $100 worth of parts and 2-3 hours job. The carbon fiber "aftermarket replacement" are only the airbox, NOT the intake.