Inertial reel shoulder/seat belt- Securon

My car is never going on the grass at Pebble Beach to compete. I want it to stay “relatively” true to its roots and to look period correct…to a degree. The stock shoulder harnesses are a pain in the butt to adjust and once belted, unless you leave it loose, defeating the purpose it’s difficult to move around. The spousal unit also dislikes them.

I looked over some old posts about a company in the UK that makes inertial reel belts for the Jag and I sent them a note, but haven’t heard back yet. I was hoping to be able to use the chrome tab and receptacle, but if I have to given them up, that’s ok. The company is Securon, the question is, is anyone aware of a US company that sells these too?

Second question, I read somewhere on a US site that the Securon reel needs to be mounted vertically. I had intended to mount them on the higher on the b-pillar behind the passenger and drivers seats where the belt snug fitting is located. This would imply that they need to be mounted on the floor behind each seat and I’m concerned that there might not be enough room. Thoughts?