Then a Byzantine Spain? You are evil AlumaThe Byzantine Empire
Let go of Greece and Rome
Both Italy and the Balkans are a thorn in the Empire's long time survival and essencially useless
Have Heraclitus keep Egypt and the rest of North Africa and remain Emperor in Carthage while Phocas's Kingdom and Sassanid Persia burn in the grave they made for themselves instead of wasting your forces fighting them, building them up instead to face the inevitable adversary that as it would turn out would be the Caliphate while estabilishing better relations with the Pope and whoever rules Italy at that time of the week
Make sure to also keep the whole Hispania as well
Then, if things work according to plan, there will soon be a whole New World that will be roman
Now I may try to do this in EU4