As jeffff stated, it is possible for a 70 year old to donate organs.
According to the Department of Health and the Mayo Clinic:
There is no absolute age limit for organ donation. In general, organs may be donated from someone as young as a newborn or as old as 75. Depending on the tissue in question, the age limit for donation is below 80 for cornea and between 16 and 60 for long bones. There is no age limit for skin donation.
There are very few absolute contraindications for organ/tissue donations. For example, patients with some infectious diseases or cancer (except brain cancer that has not spread) may not be suitable for organ donation. The medical team in charge of the transplant will assess all potential donors individually for suitability of the organs/tissues for donation.
So, yes, it is possible, that if a 70 year old has no heart disease, the person's heart could be eligible for transplantation.