Yeah - that would complicate matters! I'm lucky, in a way, that I didn't go with a donor car, but rather, pick bits & pieces from all kinds of different vehicles to suit my particular needs. It's certainly more expensive this way, but I rarely have to compromise on anything - I can just find what fits best, rather than modify the car to fit the parts I've got.
I don't suppose you can slot the seat for the belts to pass through?
If you're using retractor-only belts (not inertia reel), you do have more options on where to mount the reels. On inertia reels, the retract mechanism has to be mounted on a precise angle, or it will simply stay locked, and you can't stream out the belts to do them up. I have Miata seats, so I have a triangular space behind the seats where I've mounted the reels, near the floor, & vertical. It took some fiddling to get it all to work.
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Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.
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