A 2-speed pump is quiet and cheap to operate; glad you found one.

Never had to buy any of the long machine screws; always had access to a broken motor I could rob, if needed. Didn't find any listed, either. BUT you could possibly get away with using double-nutted all thread rod, in the appropriate size.

If you can't find the rod you need, call this company: http://www.walterwood.com/ . They are local to me, but they are online now. They don't list the rod, but they have it in stock -- probably in both coarse thread and fine thread stainless.