Nothing wrong with using a crankset that is designed/labelled as 9-speed with an 8 speed setup. That's what I have on my bike now, and it shifts really well. With that in mind, there are a plethora of options, especially if you want to stick with 22/32/42 or 44. Do you already have a BB installed? I not, do you have a preference for BB type? Do you want to go triple or double?