General: 850: Securon seat belts

[lverona]

Hi all, I know this subject comes up regularly, but I can assure you that I've read all the posts regarding the short seat belts in the 850!
I'm looking to pick up an 850, and have found out that my babies car seat won't fit due to the short belts.
The obvious answer is to buy a different car seat, but for many reasons this isn't an option for my wife as she has picked the kit we've bought specifically.

I also know that the seat belt extenders aren't considered safe for securing child car seats so that isn't an option.

Securon sell a static belt for the rear of the 850 which is 220cm from bolt end to end, and up to 47cm for the bucke.

Does anyone have any idea how long the standard belt is, so I can see how much longer the Securon belt is?
Alternatively, does anyone know how much longer than standard the Volvo replacement front belt is?

It sounds really petty, but if our car seat won't fit in the car, then I'll have to buy something else, and I really want an 850!

Much appreciated.

Luke