You can buy straight ones, but couldn't find an angled one the right size.

The valves are M6x0.75 fine thread, very cheap off ebay. Watch out, some M6 grease nipples are M6x1.0 (ballscrew nuts I think are this size.)
Yes you are correct re the ball screw size M6x1.0 also worth noting is that if you unscrew the pip (nipple bit) out of the body that is also the same thread. In than case (although you might have done it already) if I could find a 90' nipple with the M6x0.75 thread it might be possible to take out the nipple bit and make a straight extension.