Good overclocking capability AND integrated Ultra/160 SCSI are almost never found in a motherboard. You usually have to choose from one or another. Anymore, integrated SCSI is a feature that's usually reserved for high-end server boards, not consumer-level ones. And overclocking isn't a priority for a server board, so therefore it'll have little or no capability to even do so.
My suggestion is to pick out a good, solid motherboard without SCSI and just get a separate Ultra/160 controller. This way if you ever decide on upgrading the motherboard, you're not also buying an expensive SCSI controller again. Remember, a good Ultra/160 controller easily costs $200+.