Hi Jeff, you got right first time. Well done, better than my first attempt.
I replaced the belts in my '75 for rego about a year ago. Don't know if '75 is the same as yours or not. I bought Hemco belts for mine. I threw away the packaging, so I don't know the part # now, just remember that I had to ask for 230mm stalks. The Hemco belts pull in a different direction so, for the retractor mounted over the wheel arch, I made up 1/4 inch thick steel angle brackets. Drilled one hole for the body mount, another for the retractor mount. Pretty simple really. Pity I don't have photos.
Are you registering LHD or RHD? (and I'm presuming the car is a recent import) If RHD, it will have to be Engineered, questions may be asked about the seat belt mounting. If LHD, it only needs a Blue Slip. It's unlikely that the Blue Slip guy will want you to pull the trim apart so he can inspect the seat belt mounts.
Hope this helps.