i think you will find that you will have to weld a 50mm x 50mm plate around the bolt hole for a blue plate
or find a pair of factory mounts that were spot welded to the under side of the floor [ i may have some ]
then you can say they were factory fitted
Rob
Have plenty of body washers from belts out of my old sedan, the floor under is in good nick, no cracks, I like the idea of a bar underneath between the two bolts, maybe weld the nuts to the plate...
Called a local place that does blue plates for extra child seat anchor points, he can give me a blue plate for this...but hes on holiday till after easter...bah!
Jemahl