Has anybody put oil coolers in the longs? if so what type and how well did they work?

you'd probably be the first...

for a cooler to work you must have good airflow to the entrance of the cooler, and you must have good airflow away from the cooler. if you don't have airflow, you can use whatever kind of cooler you want, because it won't work ...

I'm thinking of venting front and back so as to get good air flow

you're going to need to post a picture or a better description of your proposed "venting".

you'll need more than just cutting a hole at the front and the back.

you can make almost anything work with enough time, effort, and money.
you must also ask yourself why, in 35 years, no one else has done this...

Time & effort I have it's the money I'm a little short on.Thanks maybe need to rethink location was just a thought

thoughts are good.

i believe there is still room for innovation in these cars, even if they are 35 years old. but some things don't change, and heat and air are two of them.

i do not believe that -everything- good has already been thought of, but lots of very smart people dedicated to the goal of making the 914 better have invested a lot of effort into seveloping solutions that work. wherever possible, check out what's already been done and proved to work.

let me go back and ask a basic question - why do you think you need an oil cooler?
do you have a calibrated oil temp guage that is showing you oil temps over 230F in your operating regime ? is this a dedicated track car? do you live is a very hot climate? have you checked the existing on-engine cooler for obstructions? do you run the engine in too-high a gear?

if your car is not overheating, leave it alone. if it -is- overheating in a normal street-car environment, something's broken - find it and fix it.

if you have another reason the engine is running hot - maybe you have upgraded it with lots of displacement, or you're running air conditioning in Yuma, or it is a track car, you may have a real reason for needing an additional cooler.

Here's my cooler set-up... works great for me.