Won't block off plates force additional CFM of air over the oil cooler fins?

The offset mounting holes only allow the Tstat to be installed one way, the correct way!

yes.

Correct. I have intentionally tried to mount the thermostat backwards, can't be done (at least not without significant effort).

My sentiments exactly...

Update-

This morning I replaced the solid oil pressure relief valve piston with an older style piston with the holes.

I started the car and it took significantly longer for the temperature to rise. I also noted that my oil pressure seemed higher.

I took the car for a drive of about 10 minutes and the temperature rose to just below 210. I drove the car for another 5 minutes or so and it went to just above 210 and stayed there.

Since the car appeared to be running cooler and seemed stable, I decided to take it to my independent Porsche shop and have them look it over and test the Air Fuel Mixture, check the exhaust emissions and maybe do a compression test. I also asked them to dig a little deeper into why the car appears to be running hot.

I drove the car about 40 miles and the temperature rose only to about 230 before it stabilized and stayed there for the remainder of the trip.

The car seems to run fine and never skipped a beat the whole ride. When I got to the shop I started to think that maybe the gauge is somehow off. There really was no evidence of the car running hot other than the gauge.

I will provide an update once the mechanic has spent some time looking the car over.

Thanks again for all of the great feedback and advice.

So.... might your location be mentioned? I promise not to tell Obama.

Sounds like a huge change. I'm glad to hear and I'll keep that in my mental notes for when I build or buy an older engine again just in case.
Cool

210 is pretty normal. 230 on a hot day maybe... those are acceptable especially without a front cooler. I would consider the case closed but you may find slight improvement with the services you've requested.

good deal. i suggested early in the thread confirming oil temp in tank with a meat thermometer or mechanical oil temp gauge. that will tell you if gauge is off.

+1

Good job.

Regarding block off plates ... you'll get more air across the top. But the bottom acts as a heat sink with no air moving through exchangers. Also, the exhaust side of the heads are naturally hotter anyhow. So no air flow through exchangers will compound this affect.

Maybe you nailed it early on.

Is it a Fram oil filter by any chance?

http://forums.pelicanparts.com/porsche-911-technical-forum/733760-oil-filters-interchange.html#post7272986