1200 mile road trip - and overheating question

[ReeseBobby]

Well, I've had my truck (1970 C/20 4WD) for just about six months now, and I finally have her in a state to take a long road trip. This past week I drove her out to our hunting camp in Eastern Oregon. Way east. The trip was 473 miles each way, and lots of driving on BLM roads and off road during the hunt. I had swapped out the axles from the original 4.56 with drums and replaced them with 3.73's with front discs. On the highway I ran a steady 65 mph the whole time with nary a complaint. In the mud, she ran like a top, and you couldn't get her stuck if you wanted to. I had installed FatMat thru the whole truck and then put about 45 square feet of closed cell foam and MLV under the vinyl floormat. I have dual Flowmaster 50's, so she wasn't quiet, but it was manageable. At surface street speeds, she sounds fantastic. I installed a radio with indoor/outdoor speakers under the bench seat that worked via Bluetooth off my phone, so I hardly noticed the drone. Although it reminded me of being in an airplane and made my wife fall asleep.

The only problem I ran into is the one I need advice on. I don't have an overflow bottle on my radiator. On the way home, when I stopped for gas, I noticed antifreeze was overflowing out the tube onto the ground. I didn't think it was a big deal until the truck started to overheat. When I stopped, a ton of fluid was venting out the tube. I let it cool, and found the radiator was almost empty of fluid. I had filled it with about 30 oz. prior to leaving camp, so that's how much I lost on the whole drive there. I added water back to the radiator, and when I started her back up, the temp immediately went back to normal. I drove her the rest of the way home without a problem. However, the radiator was way down again by the time I got home. I notice the bottom of the radiator is cool, but the top is too hot to touch.

If I add an overflow bottle to the radiator, would this solve the problem, or is it something else? I don't know if the heat and run-off is a function of the long drive on the highway, or something has failed. Any advise would be appreciated. As I know you all love pics, I will post a couple of the old girl at camp. Thanks for your help.