radiator hose routing

Pulling from the top means once your coolant level gets even a little low you’ll be sucking air not coolant. Once that happens things go downhill rapidly.

Fabricate the long hoses...definitely.

Have you considered perhaps this radiator is not an ideal solution in any way at all?

Also how did you plan to get the air out of the cylinder head if the top of the radiator is below that height? Is there a bleed valve up there?

944 radiator is typical aluminum with plastic tanks.  I actually have two of them. 

Like many cars, the radiator sits low in front and there are expansion/fill plastic tank that are
above the water line, with the narrower 944 radiator, it can sit even lower and a little  further forward.

Because it is a PORSCHE radiator, you know it will make the car handle better. 

This is the stock mx3 setup, I updated it to a slightly different setup used in the later model mazda 626.

Looks like it will be ok with the crossover hoses, I have some 1.5in aluminum tubing.

Here is a pic of a 944 radiator, it has nice shroud with good fans.

I did the cross over hoses, not a big problem really, just a small one as one of the hoses running in front of the fans was cut into by a fan during the Northworst race this weekend at The Ridge. was a simple fix at the track, readjusted so rubber was between fans, problem solved.

However, we still had overheating issues with the bigger radiator and good fans.
Car was fine when colder in the morning, but afternoon and it would hit 240F when running it hard.
Our two newbie drivers running not-so-fast never had heat issues, but our two gunners would get it hot and it blew the 14lb cap once
on sunday afternoon.  This was the same problem we had before, when I toasted the last engine. 
We made it through the whole weekend though, so that was great. 
All the plugs before showed it running rich, have not looked at them yet this time.

We added some ducting sunday morning and didn't seem to help, but it was a rushed poorly done job.
I am just not sure what needs to be done.  I've been told these KL V6 engines run hot, but there must be a solution.

Would adding an oil cooler help?  Even bigger thicker radiator?

Reading plugs is not reliable. To tell if it’s running rich or lean install a wide band.

Make sure your lower radiator hose is not collapsing. It either should have a spring inside most of the length or be made from rigid pipe.

Otherwise, look for restrictions on the air side. Also look for ways that air can bypass the radiator.

So, the only way that I was able to get my first 24 HoL build (V8 SHO) cool, after many iterative attempts,
was to install a Ron Davis 2-pass radiator. I think I killed three, maybe four, engines before that solution.

I like the oil cooler idea, mostly because I already have a couple from the rx8, so budget friendly. 

I do have a wide-band O2 plumbed into the new headers, but did not have time to install it to record the readings over the runs.

I really don't know how the air flows, anyone have a wind tunnel I can borrow for a 12 pack?
Or another easy way to measure/see it?   smoke while towing it on the trailer??
Or just some high powered fans?  I have a pretty powerful one in the shop.

Looking at the car, I do see that without the headlights, the air can rush into the engine compartment
from the open holes, that might be an issue, I should seal those off, we plan to run ducts to the brakes though them, but haven't done it yet.

The fans are on all the time.

I know the best approach is like lotus does with a hood opening to vent out the air, but there is just no room in this small car to do that properly.  I saw how the Rotary Rooter guys have theirs setup, but no room to do that in this car.

Oil cooler will help. Ensuring the car is running the right AFR will also help. But don't over think it. Basic approach is make sure all the air that hits the front of the car either goes through the radiator, or is deflected away somewhere. Air will take the path of least resistance, so if you have gaping holes where the headlights were, air will go through there, then pressurize the engine bay and make it so the radiator doesn't see as much air flow as it needs. Seal off every hole in the front end that isn't the radiator or other coolers.

It wasn't asked, are you sure that 944 radiator is clean inside? They can gunk up and become less efficient over time. It's possible that the 944 rad is actually less helpful than a new stock MX-3 radiator. easy check is to get the car up to temp so the thermostat is open, then check the radiator for cold spots (ideally with an IR thermometer, and not your hand do you don't burn yourself).