[W126 Coupe] Engine swap maintenance

[Josh Allen]

Ok, I posted this over on MercedesShop, but as it's a coupe, I'll ask 
here as well.

I'm currently waiting for an engine to replace the crunchy one in my 
500SEC, and want to do all the routine preventative maintenance work 
before I drop it in the car.
I intend to switch over to MegaSquirt EFI once I have the engine running 
reliably, mostly just because I can, and to see what it does for 
reliability and fuel economy, and eventually for power.
With this in mind, I'm trying to avoid sinking much into parts that will 
be removed with the change to EFI, but to also try to take care of parts 
that will see higher wear, if I ever get around to going with forced 
induction.

Following is a list of parts that I'm interested in swapping out, but 
I'm open to suggestions of parts that should be left off, or that would 
be well to take care of while I'm at it.

Thanks for any suggestions and advise!


Timing chain
timing tensioner rail
Timing chain guides? (the rest of them?)
valve cover gaskets
cam oilers
rear crank seal (rear main seal)
trans torque converter seal (input shaft seal?)
any hardened rubber fittings
injector bushings? (planning to swap to MegaSquirt relatively soon, so 
this is low priority)
motor mounts
transmission mount
flex shaft disks/center bushing block
intake upper/lower half connection donuts (8 rubber rings, whatever 
they're called!)
oil pump chain/tensioner?
front crank oil seal?
valve stem seals?