2000 grandam

Listen to this! Can anyone help?- Recently my 2000 grang am had major probelms, well atleast I thought. I took it into a certified pontiac dealer, and was told that there was major head damage and that it would cost several thousands to fix. So my father, being not only a retired gm employee but a mechanic of over 30 years refused to allow the dealership to continue fixing what was wrong b/c it wouldnt be worth the cost. SO, we went out and found a used motor with only 35,000 miles and took out the old motor to put in the motor we purchased only to find out that the only thing wrong with the original motor was a broken fly wheel which is easy and cheap to fix, certainly not the cost of the motor we bought. Now I have two motors and the pontiac dealeship obviously lied to us, telling us that the old motor was in need of rebuilt heads. I am trying to sell the original motor but its difficult. Does anyone have any advice??

sue