I checked with Ferry County and the State DOT and learned the following:
Washington State Route 21 SR-21 is being prepared for chip sealing to take place beginning Monday 7/23/2018 The patching and pre-sealing is finished which means SR-21 will be rideable during the rally but you should be cautious when encountering these patched areas. This SR-21 project runs from South of Wilbur in Lincoln County up to Keller Ferry and from the Keller Ferry to Republic
Not in the Republic area, but you might be considering Chumstick Highway between Leavenworth and Plain is undergoing chip sealing this week and Highway 97 over Blewett Pass is getting guardrail replacement where one lane will be closed leaving two lanes in places. SR-17 is getting some resurfacing early in the week in the Ephrata to Coulee City area among other areas. SR-25 from Kettle Falls to Northport is undergoing some construction requiring a possible 10 minute wait and pilot car escort. This work should be completed by Saturday.
It is always a good idea to check with WSDOT highway maintenance schedules prior to any cross state ride.
After learning of major chip seal work 7/16 on Toroda Creek road and Molson road, I eliminated the North loop and added two new routes that avoid the chip seal work.