SORRY FOR DOUBLEPOST!
But I just found something quiet interesting, according to a thread on mmochampion.com (
100% haste..) 100% haste= 50% casting time reduction, if I am right, correct me if Im not, this means that with this build
chardev 9 with 12 haste or 31.2% haste you will reach a 1.5 / 100 * 31.2 = 0.468 / 2 = 0.234 decreased casting time.
Further more, according to chardev, 1 haste = 2.65% haste at lvl 1. This means that when using LB (35 haste or 91% haste) on this build, you will get a 1.5 / 100 * (31.2 + 91) = 1.8375 / 2 = 0.91875 decreased casting time, meaning your Lightning Bolt will take around 0.58 sec to cast while still having 38SP.
If you want more SP you could always switch 10 haste with 16 SP, 9 sta with 7 int or 100hp with 4 stats.
Though switching 10 haste will increase your casting time with 0.195. 10 haste = 26% haste, (1.5 / 100 * 26) / 2 = 0.195. But this will still increase your casting time with LB by 0.91875 - 0.195 = 0.72375sec.
I dont know if all this is correct, but if it is, it seems to me that 22 int wep and shield is the way to go, since the 20 haste wep will decrease your casting time by: (20 haste = 52% haste (+2.6% because I chose the 2h mace wich has 1 haste) So it will be (1.5 / 100 * (54.6 + 31.2)) / 2 = 0.6435, meaning you will be hard capped with 20 haste on gloves, even without LB and zerk.