PFC is a good, easy solution to upgrading a computer.
As Angus mentioned, the PFC is still available for R32, R33 and R34 GT-Rs, so you shouldn't have much trouble finding one. Most sellers offer them with hand controllers anyway, and it opens up your options for finding a workshop to tune it for you. Try sourcing one from Sliding Performance, Aaron is a good guy and he's in Qld too.
Both s1 and s2 260RSs use the R33 GT-R engine and driveline, so use the R33 PFC. For a boost controller, try the GReddy Profec B Spec II - I was gonna buy the Apexi boost controller that plugs into the PFC for when I eventually install mine, but the GReddy unit is bound to be just as good, and a lot cheaper (shop around), so I'll go for that instead. I need to fill the hole in above my Defi controller anyway, so this will fit almost perfectly in that little hole.