You got it right. The H in HP denotes the model year, 1950.
The C/K designation didn't come about until the '60 models. C=conventional cab 2WD, K=4WD.
For resto packs, there are only the two choices--car or truck. As long as you are getting the truck pack for your year, you're OK. The truck packs cover all models from 1/2-ton to 2-ton.
