need different shocks for wider a arms

[dart450r]

ok... i bought a set of used a arms from Gilco (i think it's his screen name) i am using the stocks shocks right now. but i'm pretty sure it needs longer ones... the stock ones seem to be 9 1/8. i think i could use something around 10 1/2, maybe a tad longer, not to sure. he will be doin edt and trail riding, being that said, i know they will need to be stiffer than the stock ones. any ideas of a shock that will fit this application other than buyin works or what evers? these are only the single a arm, not dual set-up.
thanks