An organ has meaning while there is a heart beat. An organ helps to sustain life. Once life is gone from that body, an organ has no meaning to that body. It will either be burnt, or buried - but it will surely be destroyed. This organ is surely not going to heaven, or anywhere.
You can add to your noble deeds, and karma. You can save many human life by donating your organs. In fact, not 1 life, but 8. Make your life count even after your death. Save the life of 8 dying men. The prayers of them, and their family will reach your soul in heaven. Pledge your organs. Don't think. Just do it.