I tried to get a Syrian visa in Amman, but was refused, since I'm a Canadian citizen. They said that the Syrian embassy in Jordan grants visas only to Jordanians. So I crossed border to Israel and took the ferry from Haifa to Piraeus, no problem. There is a regular ferry from Nuweiba, Egypt to Aqaba, Jordan. I suggest you try to get Syrian visa in Cairo. If you don't get it there, you can cross Egyptian-Israeli border near Gaza, and save yourself the detour through Jordan. On the other hand, there is lots to see in Jordan on the way north, e.g. Petra, etc. The choice is yours.