Well, I tried to get it all in the title of the thread, but can I do 290mm or 288mm spokes for both sides front and rear? Using DT comps in black with the supplied brass nipples.

Velocity P35 rims, Hadley 9mm front ISO disc
290 front left
289 front right

Velocity P35 rims, Hadley 135mm rear ISO disc
289.5 rear non drive side
288.4 rear drive side

Can I get away with buying one box of spokes or should I buy both sizes? What do you think?