pete im not a widowhood flyer im natural i think the birds you have should be able to handle those distances my guess would be the lenth of time your birds are in the basket for these races as my birds can be away 3 4 or even more days in the longer races i want the birds to be calm or by lib time there burnt out if to keyed up so i would not be showing them there partners as i would think it would get them to worked up and aggitatated when they have to spend a few days in the basket imo bowls should be enough m8