I first saw the original when I was 6 and GB2 at the cinema when I was 8, my nephew saw GB1 when he was 5, found it a little scary but just want s to see slimer and Stay Puft lol. That was a year ago and he still loves to watch it when he stays with us, last week most recently.Fair then I am wrong, I'll still rewatch to make sure it's suitable though
The second is a lot more kid friendly as it was after the cartoon got popular so no smoking or any bad language etc, ghosts were more btightly coloured etc. 1 does has constant smoking bit of swearing and that scene with Ray and the ghost but as a kid it'll probably go over their heads.