go to yahoogroups.com, type a search on fzr400. there's a huge mailing list there.
there are two different ways to build 560's. keep in mind i never built either one, but here's a rough idea of how it's done. jason clay the list's founder has built a few of them and there's still some out there. a lot of the fzr parts that are hard to get are either eliminated in the 560, or still easy to find on the mailing list.
spacer plate (the bad way). take one fzr400 case, add fzr600 crank and 1mm over 400 pistons and a 23mm or so spacer plate between the cases and the cylinders. you'll need at least 600 carbs and exhaust. read www.armyofdarkness.com
to see what your definition of reliable is compared to the spacer plate 560.
the new way. 400 cases, yzf600 and crank, fzr600 cylinders, yzf600 head fzr600 1mm pistons and yzf600 carbs. they say at 85 hp, it's still reliable.
there's also oil sprayers that you should add (i think they source these from air-cooled gsxr's and some machining. keep in mind, i've never done this myself, so not all of the facts will be correct.
anyway, it's probably cheap to buy and refurbish one that's already built than to build one at this point.