Dodge Raider seatbelt problem

Hi, my driver's seatbelt doesn't seem to be working ok, when i hit a bump or ditch i come out flying off the seat and sometimes i hit my head on the roof (wearing safety helmet).
I have the passenger's side seatbelt lying around unused, can i replace it?, if you place one against each other they have the same pattern but in mirror image.
Or can i simply extend the seatbelt to my size and glue the round metal piece that makes the yellow lever block the white wheel to stop spinning and turn it into a fixed length seatbelt?
I'm not planning to put money on this because i wan't to upgrade to a race seat with 5 point restraint harness.

driver's side

passenger's side

mechanism