If Sedevacantists REALLY want to go back to the teachings of the traditional church, they can follow this chain of conversions that gets closer and closer to the Early Church, going all the way back to the apostles:
1. Traditionalist Catholic (broke off from Orthodox c. 1054 ad)
2. Eastern Orthodox (broke off from the Proto-Anglicans in 500ad)
3. Proto-Anglicans (broke off from the Pentecostal Lutheran Synod of Eastern Sicily, PLSES for short, in 304ad)
4. PLSES (broke off from the Baptist Roman Conference in 232AD)
5. Baptist Roman Conference (broke off from the Southern Baptist Convention in 55ad)
6. Southern Baptist Convention (established 33ad)
As everyone knows, the SBC is the true church established by Christ. It is the most traditional church, and our Popes (the best being Pope Charles II of Spurgeon) have preserved the faith through the millenia.