Help! 360 with 302 heads no compression

I couldnt tell if it had anything done with it. The pistons didnt have any number on the top of them saying of they were .30 or so. But its possible of its been rebuilt in the past. Also i thought it was strange to use a tensioner. I went to a speed shop and the guy pulled out 5 different timing chains for my truck and they were all the same. I talked to a few members on this website and they said they used the tensioner before. It was for the 3.7 v6. The truck seems to run fine right now. But only time will tell