Bleeding them can be a pain sometimes! Be careful with the allen bolts as they can sometimes be stuck on pretty hard although if this is a CA car then you may not have any problems there. If one gets stripped or just won't come off then you just cut the head off with a sawzall or something similar, the rest should turn out with your fingers when you get everything else off (it seems it is just the head that fuses on).
What are you doing with the car, it is a track only or street too? If race only you might consider replacing the rears with Spider calipers as they are a lot simpler to deal with. The reason I say for track only is that you lose the emergency brake if you do this. They take the same pads.
When I replaced my rear calipers I had the car on jackstands and was unable to get satisfactory leverage to really reef on the bolts. I took the car to a local shop (along with a brand new allen socket) and they put the car on a lift which made it possible to get a good pull with the breaker bar. The bolts came loose with no problems. Snugged them back slightly and drove home. It cost me $20 bucks-the minmum labor charge. Make sure there is no crud in the allen heads as it's imperative that the socket seats completely.
I have a lift, still had the problem , depends on the climate that the car spent most of its life in I think. My driver Verde was no prob but it was from CA, any local (North East) Milano has always had at least a couple that had to be cut off!
I always use an allen headed socket with a long extension which allows me to use the huge breaker bar while sitting by the side of the car with the wheel off. The long extension also means there's no side load on the allen head so less chance of rounding it out.
Give the end of the extension a whack with a hammer first to make sure it's all seated properly too.
I'd love to use Spider calipers on mine, especially as we sell these-