Racing seat belt install

I have been looking around and have not found a good topic that helps me. I have a 1972 Pontiac Ventura and do not want the standard seatbelts. I want to put a racing harness on each of the front seats, but I want to keep the back seat functional. I know I can install a roll cage to attach them to, or go to the rear deck, but like I said, I want to be able to use the back seat. Any help or links to other threads would be great. I know there has to be a good thread on it, but I have not found it yet. If it helps, my car is basically a Nova.

Thanks for all the info. I really appreciate you telling me not to mount to the floor, because that was the only place I could think to mount them and keep the back seat functional. Under the rear shelf there is an X frame back there that I thought I might use for the rear mount. Do you know if there is a roll cage that will allow people to squeeze under that is not too low?

Head what the techie guy tells ya, for improper belt installation WILL GET YA HURT at the very least !!!!!!!!!!!!!!!!!!!
And I would suggest in a street car with no cage and stock fold back seats your best option would be the stock shoulder/lap belt as there is no way to correctly mount the race harness. But if it is the older ventura that had nothing but lap belts and your dead set on racing belts you could get away with using just the racing lap belts...

Couple of issues here. If you want to run the shoulder harness, you'll definitely need a "roll bar" with a horizonal brace. This is for two reasons. First, in running the belts rearward, tech inspector is correct; you need to direct the force rearward instead of downward. You can run a second horizonal brace below the first to attach the belts to. Second, when using these style belts, you need roof protection. These belts will keep you planted. If you roll the car and the roof crushes, your head would be the next form of support.

I would also try to upgrade the seats if you go this route as well. Newer seats are considerably stronger than OEM seats of the '60's and '70's.

I saw a guy autocrossing his Neon and he rolled the car. He had no cage, and with his belts, he almost broke his neck. His helmet was cracked.

Now in running a cage or roll bar, the rear seat will be useless. You might want to check some mid-'70 X-Body cars to see if you can retrofit an OEM three-point seat belt if you don't want to run the cage.