[dsraven]

from personal experience, if I could go back, I would surely secure the seats and the seat belts properly. in a dune buggy rollover accident I was thrown clear of the buggy only to have it roll over me and break all the ribs off my spine (except the floaters) on one side. it teetered on top of me on it's last roll until it finally fell off (yup, the engine end of the buggy of course) so I was all out of breath. luckily I got my wind back before passing out and was able to drive the buggy back home so I could drive my 63 gmc (std steering) to emergency. moral of the story is: fasten all belts and seats properly and make sure the welds are done properly etc. my issue was a friends buggy and the seat belts were attached with some pretty bad welds ground off and painted which let go under the pressure. that is the reason my project has seats with integral shoulder belts. I am not using a stock floor but if I was the seats would be bolted to the floor and then cabled to the frame under the floor so if they let go they couldn't go far (hopefully). a bench seat would be secured to not tilt so there could be no way for the grand kids or others to be injured by the seat or thrown through the windshield due to poor belts or seat mounts.
when I was a kid my family drove around in a 59 chevy truck. 2 adults and 2 kids. no seat belts. not a problem at the time. I would definately not do that in today's world with access to all the safety items we have today.

end of rant, your truck, your conscience, your decision