It's been almost ten years since I last done any of the back end math for this kind of thing, but you could probably get within the ballpark using COTS rubidium

It's been almost ten years since I last done any of the back end math for this kind of thing, but you could probably get within the ballpark using COTS rubidium oscillators like those used for cell towers. They often show up on auction sites at affordable prices. Use the pulse output to lock a station clock for your local time needs (like syncing your data recording to wall time) and the sine output to lock your mixing oscillators.