Like someone else said, I would try more specific compliments so he knows exactly what about him you find so attractive.. eyes, arms, chest, etc. It's a generalization, but many guys are competitive, so maybe saying he has the "most handsome" most irresistable" "best arms," etc.
I can think of plenty of synonyms, but they all sound feminine or just don't suit him. When people have exhausted their resources, it's generally acceptable to ask others for help or advice. So, no need to be a dick.
I had a boy like that, and the thing is he didn't like being fawned over, so every now and then I would tell him how glad i was to have such an incredible handsome man as my own...he seemed to like that