Poncirus is the Main rootstock here. The reason is Not only tristeza. The biggest nurserys are found in Delta of Neretva River, which is the only big comercial Area of growing Citrus and that Valley is quite cold so they , AS Major producer, use mostly poncirus
I think you should try to get hand on rootstock Forner Alcaide Nr5. It is said to be much more tolerant to high lime-level in ground and should be as resistant to CTV as Poncirus is. Otherwise there will be endless trouble with deficiencies. Also Poncirus is said to be inkompatible with Eureka lemon.