OK, so high temps are not an issue as of right now. I changed the belts and that helped a little, but I still had a climb over 205 that I didn't like. I decided to see if there was any air left in the system. I parked the truck on a slight uphill incline. I let it run with the radiator cap off and a piece of cardboard stuck behind the spring of the throttle cable (to get it to 2500 RPMs). I let it run for a good 20 minutes like that. I didn't need to add much coolant at all, but I did notice the coolant looked a little rusty after the t-stat turned on the third or fourth time (it was not oil). I know the heater core was clogged up bad when I bought the truck. I remember the rusty gunk that came out when I flushed it - I am thinking I should replace that anyhow.
After that, I drove the truck in 4-low up and down some decent size hills for about 30min. I also got it up to speed in 2-high. Never went above 200. So problem solved, at least for today. I am thinking there was some air in there, or some blockage finally broke loose.