Plenty of eights, will check for 7's. I've made 7's from 8's in the past, just leave 2nd from bottom off. Ideally go with 12-23 or similar, lose the 13, add a thirteen closing sprocket.
well sadly I don't have a lot of workspace so "like for like" is always favourite for me ! How much for the wheel/ cassette combo assuming you can source a seven ?
