Too old? No. I have seen SIU guys come out in thier 60's as a second career lately. As far overweight? I cant speak for SIU, but I believe if your BMI is over a certain percentage you have to do a few more "tricks" during your CG physical. Meaning you have to crawl under a limbo stick and jump over it or something. They want to make sure meet the physical requirements needed at sea.