Something is really wrong IF you are overheating at speed. Try the stuff already mentioned. You should be loosing a lot of water due to not having a puke can with these extreme heat cycles. Is the system even pressurizing?(dont pop the cap, squeeze a hose instead) If not then you arent hot. If you overheat at idle, try idleing with a garden hose running in the radiator. 

Thanks for the advice Charlie,
Here's what I know. I've actually changed the thermostat twice, the first time because I was a bit ignorant on the workings and thought getting a lower temp thermostat would make my car run cooler.. also I wanted to make sure I installed it correctly that first time. The one I have in now is a 180 degree thermostat I believe and yes.. before I put it in I did the boiling water on a stove trick to see if it opened properly which it did.
On the water-pump, it's actually a brand new water pump. A while back I posted a picture of the original which had a  scale covered impeller and the guys on here said to change it.
: )

Well that's quite a thing isn't it? When we got off the highway where it was reading 215 degrees, I was looking at the radiator and there definitely wasn't anything I would refer to as 'puking.' By the time I'd got out and got the hood open there was just about half a glass of fluid on the ground and no more was coming out.. if so just drips. But we TESTED the gauge and thermo on a stove with water before we installed it! Bad heat pocket in the engine around where the termostat is perhaps????

-Fan belt? Maybe, I tightened it to the flex limit the original manual shows and I've never heard it squeal while driving.
-Yes the lower radiator hose has a spring in it.
-Fan stopping? You mean like having it installed backwards? I guess I could check, I did take the fan off to change the pump.. pretty dang sure it's on right though but I'll check again.
-I've only taken off one head while I've owned the car, the head on the passenger-side. I was incredibly careful every step of the way though, took pictures too that I could post if you want to make sure it got put on right.
-That's going to be my second guess if this doesn't fix it. I'm really hoping, are there shops that will deep clean your engine block if it IS full of sediment??
-I don't see how, we tested the temp gauge and sending unit on the stove with boiling water.. and it was accurate then.

I'll check the fluid level again, but I don't think I've lost a lot of fluid. The original cap was busted and wasn't pressurizing, but we've since put a 7lb cap on there.

It does sound like you have checked most items.

RE the passenger side head gasket, where is the square corner of the gasket positioned?  Even though you didn't change the other, how is it positioned?

You could take the radiator to a radiator shop for assessment before spending money on a new radiator.

If it comes to having the block cleaned, you can probably take care of that at home.  With the block upside down, on an engine stand, use a coat hanger wire, poke around, flush with a hose, and repeat until no more debris comes out.  This is something you would probably need to do even if you sent the block out for cleaning.  Hot tanking won't remove all of that and you probably don't want to pay a shop hourly to do it.


Lawrenceville, GA

They don't appear to make stock-appearing radiators for '55 full size cars.  Only T-Bird and trucks.

The little tab, if we're talking about the same tab, is sticking out of the top front corner on the passenger-side head. I took quite a while looking at and comparing the old and the new gasket to see if the holes matched up and if any holes in the old gasket were covered in the new gasket. I put some pictures up of the bare block with no gasket, and it with the gasket put on. Something kind of that stands out to me looking at it now, there are two channels on the bottom corners near the bolt holes that look like water passages. But on ever gasket I can find online and on mine I have installed, they're covered up. Man I really wish I had the old gasket still or a picture of it to double check. But surely that can't be a design flaw in the gasket!






Unfortunately I don't have the equipment to lift the engine out of the car at home. : /

??
http://www.usradiator.com/radiators/ford/fairlane.html

That gasket is installed correctly.  What about the driver's side?  The corner should be in a similar position, front, intake side.

Tool rental places often rent engine hoists and stands.  Could be a cheaper option than paying someone to do it.


Lawrenceville, GA

The gaskets that were on the engine when I took the head off (I'm assuming it's the same on the other head) are metal gaskets, they were completely metal I wouldn't be surprised if they were the originals from the 50s. There is no tab for those.