I bought new inertia reel seat belts for my 1000 sedan from Repco in the mid 80's I used all the original holes, but need to go back to exchange the buckle part. These came with a self supporting cable & were available in diferent lengths. The 1000 mounting is in the back floor area & i simply needed some with longer "stalks" which i got with no problems.

They worked a treat, but i regretted buying them because the original 1000 seat did not offer a lot of support & the original belts held me in quite nicely. The inertia reel ones offered no support at all & it took some of the fun out of a hot run up the Razorback mountain near Sydney.