Holes in boot floor for tank

[TroonSprint]

This project of mine keeps on throwing up weird things, and here's another. The car is a '71 Sprint FHC. I thought I would trial fit the new aluminium fuel tank today. First thing I noticed is that there is no hole in the floor for the rear-most tank mounting stud. Then I spotted that the two holes for the front studs are not parallel to the front of the boot, meaning that the tank would sit at an angle, rather than square with the body. See photo.

I don't believe that can be right. The tank must be designed to sit square in the recess, mustn't it? Being a Sprint the spare wheel carries a 155 section tyre, but although it's tight it will go in with the tank sitting square. So how come the holes (which look original) are out of line? And how come there's no third hole? Baffling isn't it.

Mike