I've spent a lot of time researching kuhlis, although I can't boast that I have kept them yet. I just thought I'd add the decision I've come to after a lot of discussion and reading about it.
I think the thing kuhlis need more than space is a lot of friends. I wouldn't keep just a group of two because it would be very likely they would hide all the time and you'd never see them. Minimum group size is 5, from what I've been told by people who have kept loaches for ten or more years in various settings. Some say 20 gallons is minimum but I wouldn't object putting them in a 10 since I've had two people tell me their behavior is normal down to that size--social and active.
HTH with your decision about the kuhlis. I'm not sure how big the footprint of the 8 gallon tank is compared to the 10 gallon I'm familiar with so you'd have to make that call. You may want to have kuhlis with no dither (aka neons), so you can fit more in.