How to install seatbelts in my 57?

[yossarian19]

I've got a universal seat belt kit that seems the right length, though it has no instructions.
It appears to me that I can weld mounting tabs on the bench seat frame for the lap belt and somehow thru-bolt the B pillar for the shoulder belt's high mount. Might be tricky to make the B-pillar mount happen without also making it ugly, but should be possible.
Anyone have pics / advice / info to confirm (or a better way to do it?)