The circle fitting: AKA: Banjo fittings

There are two that are daisy chained like this and they are
different sizes.
Banjo #1

Banjo #2

One option is to get a custom hose made to replace one or both of the banjos like this one below (only replaces the second banjo)

See here for something that will probably help you out a lot
http://forums.nicoclub.com/240sx-isis-stainless-steel-braided-power-steering-line-install-and-review-t447029.html
If the only issue is the bolt being the wrong size I would go to the junkyard and grab a correct sized one... it will probably just cost you the dollar to get in but that bolt should be on most every Nissan PS pump car so take your pick of the litter. Hope this helps.