[W126 Coupe] Swap 83 380 to 85 500 motor question or two

[Dick Spellman]

Hi All:

I am looking for recommended list of things to renew on the 500 motor 
when pulling the 380 motor out of my SEC and prepping a 500 motor to 
takes it's place. 

Re: the SEC chassis, etc.  I already have a renewed transmission in 
place, renewed suspension, pretty much everything 2000 - 5000 miles new.

Re: the 500 motor I am removing a suspension pump and need to locate the 
correct cover plate.  The motor cams/rockers look to be in great shape.  
There is a unique idle speed adjustment 'add-on' attached to the fender 
that regulates the air slider valve.  The potentiometer turned CW raises 
the idle and CCW lowers same.  Idle is smooth, car starts instantly.  
Last time I drove this car it had plenty of power, felt strong.  It's 
been sitting now since I parked it last spring.  I drove it only once 
from South Jersey to Boston.

One question is will the new Harrison A-6 compressor on the 380 bolt 
right up to the 500 motor?  The 500 motor is from an 85 500SEL.

I will start on this project in March on free weekends.  Any advise or 
recommendations are greatly appreciated.

Regards,

Dick