Hi.
I see some chat in another thread called "Retractable lap/sash seat belts for 65 coupe ADR approved" that may help you. Check that out if you haven't done so already.
I did mine myself (a 66 Fastback) a few years back as i could not find a local shop or kit at that time. I got these engineer certified as well (as you will see in my reply - on the chat i've suggested for you).
