e58 police oil cooler

edit after your post
when I was with chrysler we did tests on oil coolers- they do work and if you are in 100 degree weather I would do it
use a spoiler/ front valance under the bumper or core support and plug all the holes in the core support except cold air to the filter if you are taking it from the grille area
Do you have front discs and a sway bar- modern radials like a much flatter tire on pavement, less body roll, wider wheels like 15's or better to clear the discs- lots of things to do to make a reliable/ safer road car
Tranny cooler get a Borg Warner 100 plate and fin cooler with half inch in and out threads- no tube and fin wannabees
use at least 3/8 oil proof and I'd run 1/2 inch do this and you can eliminate going through the restrictive radiator heater/cooler (if you are not in a cold weather area) stock should flow (at the tranny return) 1 quart in 20 seconds at idle
If your motor is not together make sure the oil galley plugs are drilled for oil squirt to the timing chain
you can also drill a small .040ish hole through the thrust into an oil passage to lube the thrust and the chain
chain is not usually a problem, the holes also bleed any air/ bubbles/ foam trapped in the oil galleys they should have be there already but check your new after rebuild ones
use a timing set with an IWISS chain- not a place for junk
if you do not have pistons yet consider the KB's and .020 over also ring set with a ductile top