I'm not a professional in radio communication but according to what I've learned while I was working on our new COM system with my team mates I try to give you some advice.
You can use the design of 433MHz antennas, you have found tutorials for, but you have to change the lenght of the antenna elements. For example you could use a groundplane antenna, here is a great tutorial on UKHAS wiki. It is easy to build, and has good characteristics for balloon applications. You only have to cut the antenna elements for different lenght than in the tutorial I linked.
The lenght of the elements should be 1/4 wavelenght. In your case (144MHz) it is 521mm. It is quite large for a standard groundplane IMHO. (There would be structural problems, but if you have big payload it could work)
I would consider to use a 1/2 wave dipole configuration at this size. You will get a nice doghnut shape characteristic with a blindspot right under the balloon, which is not that big of a problem, since the balloon usually won't stay long right above the ground antenna.
You could fix one element to the balloon line and the other could just hang under the payload. Here is a sketch of the idea: