Ah, a fellow byzantophile. I'm still proud of my ERE restoration game by 1570.Absolutely. Cover the map in imperial purple.
Restoring the Roman Empire is the best and most fun thing that EU is useful for, too. A very difficult and intense 5-10 years to recover Greece, then a tough 20 or so for Anatolia, after that you're fine, and should be able to expand more gently whilst massaging out the inflationary and reputation aches from such rapid expansion, with Rome doable by 1500.
Last time I played EU3, I ended up with pretty much the entire territory of the ERE as of ~400AD, plus Italy and a few odds and ends like Crimea, and by pure fluke France (marriage rather than conquest, and minus the east and northeast, still controlled by Burgundy). Reunified the church (Orthodox, naturally) and a colonised pretty much the whole of eastern Africa from Egypt to South Africa, plus a few odds and ends around the Indian Ocean and across to Australia and NZ. The kingdom of Bohemia was rampant over central-eastern Europe and my main antagonist. England conquered Scotland and Ireland but then collapsed into perpetual religious strife and civil war. India was re-unified as a Hindu kingdom by Vijayanagar. Spain was just there. Pretty much everything else was a bunch of squabbling small-medium states or too far off for me to care.Ah, a fellow byzantophile. I'm still proud of my ERE restoration game by 1570.