The ZX10-R shock fits well into a curvy and has a slightly stronger spring fitted than the standard curvy spring. This would suit your weight much better than the standard SV spring (someone will post the table of spring strengths and shock length now
).
No doubt someone will post that a specific after market shock is a better solution (and it is) but the ZX10-R (or GSX-R) is a good upgrade and can be done relatively cheaply. Therefore I think that a ZX10-R shock is 'the best' VFM upgrade for a curvy rear shock.